Professor  A.   0.  Leuschner 
1868-1953 


Gift  of 
Dr.Erida  Leuschner  Reicheri 


STAB     ATLAS 


CONTAINING 


STARS    VISIBLE    TO    THE    NAKED    EYE 


AND 


CLUSTERS,    NEBULA    AND    DOUBLE    STARS 
VISIBLE    IN    SMALL    TELESCOPES 


TOGETHER  WITH 


VARIABLE    STARS,    RED    STARS,    CHARACTERISTIC    STAR    GROUPS 
ANCIENT    CONSTELLATION    FIGURES 


AND   AN 


EXPLANATORY      TEXT 


BY 


WINSLOWjJIPTON,  A.M. 

PROFESSOR     OF      ASTRONOMY      IN      BROWN      UNIVERSITY 


BOSTON,   U.S.A.,  AND  LONDON 
GINN    &    COMPANY,    PUBLISHERS 
thenaeum  flresa 
1896 


COPYRIGHT,  1896 
BY   WIN  SLOW    UPTON 


ALL   RIGHTS   RESERVED 


REP.  GEN.  LIB. 

ACCESS.  NO.     7512.0 


t  ' 


la 

GIFT 


LJ7 


P  B  E  FAC  E. 


Tins  atlas  is  designed  for  teachers  and  students  of  Astronomy.  Its  aim  is  to  supply 
maps  for  those  who  desire  to  familiarize  themselves  with  the  characteristic  star  groups,  and 
also  to  include  the  leading  objects  of  interest  in  the  sky,  which  those  possessing  small  tele- 
scopes may  wish  to  examine.  As  the  purpose  of  the  atlas  is  educational  rather  than  pro- 
fessional, it  has  been  constructed  in  a  form  which  it  is  hoped  will  be  specially  adapted  to  its 
use,  and  it  contains  some  features  and  omits  others  which  would  find  a  place  in  an  atlas 
for  professional  use. 

The  maps  are  on  a  large  scale  and  are  few  in  number,  with  liberal  overlaps.  Con- 
forming with  the  plan  of  systematic  study  outlined  in  the  text  there  are  six  maps,  —  two 
circumpolar,  and  four  whose  areas  cover  the  region  between  declination  N.  40°  and  S.  40.° 
They  are  subdivided  into  four  divisions  corresponding  with  the  four  divisions  into  which 
the  sky  is  divided  by  the  equinoctial  and  solstitial  colures.  The  projection  is  stereographic, 
chosen  chiefly  because  of  the  gradual  narrowing  of  the  hour  circles  on  the  equatorial  maps 
as  the  declination  increases,  and  the  better  correspondence  of  the  equatorial  and  polar  maps 
at  their  marginal  overlaps.  The"  six  skeleton  maps  are  -reduced  from  the  larger  ones,  and 
are  designed  to  give  the  characteristic  stellar  figures  of  each  constellation  area  with  greater 
prominence  than  they  appear  on  the  larger  maps.  This  is  secured  by  omitting  the  fainter 
stars  and  the  historical  figures,  and  by  connecting  the  stars  by  guiding  lines. 

The  educational  purpose  of  the  atlas  has  caused  the  retention  of  the  outlines  of  the 
historical  figures,  which  are  usually  omitted  on  professional  atlases.  They  are  given  in 
merest  outline  and  for  the  older  constellations  of  the  northern  sky  only,  because  of  frequent 
allusions  to  them  in  literature.  Similar  figures  were  supplied  by  those  astronomers  of  the 
eighteenth  and  nineteenth  centuries  who  completed  the  system  of  constellations  in  the 
southern  hemisphere,  but  they  were  added  when  the  use  of  the  figures  was  becoming  obso- 
lete ;  they  are  of  decidedly  inferior  character  in  their  subjects,  since  they  include  such 
mechanical  objects  as  air-pump,  clock,  telescope,  chemical  furnace ;  and  they  have  no 
place  in  literature.  For  these  reasons  they  are  not  reproduced. 

The  purpose  of  the  atlas  required  its  preparation  according  to  the  best  astronomical 
authorities  of  to-day.  The  prevailing  usage  of  modern  astronomers  has  been  the  criterion 
adopted ;  where  usage  varies,  a  decision  was  necessary,  and  it  has  been  made  with  great 
care.  The  only  place  where  any  serious  difficulty  has  arisen  has  been  the  proper  location 
of  the  boundaries  between  the  constellation  areas,  in  which  there  is  no  general  agreement. 

The  epoch  of  the  atlas  is  1900,  and  the  star  places  have  all  been  reduced  from  various 
catalogues  to  that  epoch  before  charting. 

The  stars  charted  are  those  down  to  the  6.0  magnitude,  thus  including  those  readily 
visible  to  the  naked  eye.  A  large  number  of  faint  stars  rarely  visible  without  a 


iv  PREFACE. 

telescope,  and  which  crowd  an  atlas,  were  thus  omitted.  The  authority  for  the  magnitudes 
is  Harvard  Photometry,  and  its  extension  to  the  south  pole,  vols.  xiv,  xxiv,  and  xxxiv 
of  the  Annals  of  the  Astronomical  Observatory  of  Harvard  College. 

Argelander's  Uranometria  Nova  is  the  basis  of  the  boundaries  between  the  constella- 
tion areas,  and  also  of  the  outlines  of  the  historical  figures.  Behrmann's  extension  of  the 
constellations  to  the  southern  pole  on  Argelander's  plan  has  been  adopted  on  the  large 
maps,  and  Gould's  revision,  which  supersedes  Argelander's  south  of  10°  N.  declination,  for 
the  smaller  maps. 

The  designations  of  the  stars  follow  Argelander,  Behrmann,  Heis,  and  Gould.  The 
added  letters  of  Gould  are  used  except  where  his  revision  of  the  areas  places  a  star  in 
another  constellation. 

The  Milky  Way  is  drawn  only  approximately,  based  upon  the  drawings  of  Heis  and 
Gould. 

The  meanings  of  the  Arabic  names  of  stars  are  taken  from  Higgins'  Arabic  Names 
of  Stars. 

The  clusters  and  nebulae  charted  were  selected  from  Dreyer's  New  Catalogue,  the 
variables  from  Chandler's  Second  Catalogue,  the  colored  stars  from  the  list  in  Chambers' 
Astronomy  and  from  the  notes  in  Gould's  Uranometria  Argentina  and  other  catalogues. 
The  double  stars  include  those  within  the  limits  adopted  which  are  catalogued  in  Webb's 
Celestial  Objects,  and  those  mentioned  by  Gould  and  others.  The  authority  for  the  posi- 
tions and  notes  in  the  table  is  Crossley,  Gledhill,  and  Wilson's  Handbook  of  Double  Stars, 
and  more  recent  publications  of^  various  observers.  t 

The  work  has  been  done  independently  of  other  publications,  but  comparisons  have 
been  made  with  other  atlases  and  star  lists  in  order  to  secure  freedom  from  error  as  far 
as  possible. 

Acknowledgment  for  advice  is  due  and  is  gratefully  made  to  several  astronomers  and 
educators  who  have  been  consulted,  especially  to  Prof.  E.  C.  Pickering,  Prof.  C.  A.  Young, 
and  Mr.  D.  W.  Hoyt.  The  reproduction  of  the  outlines  of  the  historical  figures  is  due  to 
the  skill  of  Mr.  N.  M.  Isham  of  Brown  University  and  the  engravers  Messrs.  Bradley  and 

Poates. 

WINSLOW   UPTON. 
BROWN  UNIVERSITY,  PROVIDENCE,  R.  I., 

June,  1896. 


EXPLANATORY    TEXT. 


THE     CONSTELLATIONS. 

THE  division  of  the  sky  into  constellations  is  the  oldest  part  of  the  science  of 
Astronomy.  It  was  begun  in  prehistoric  times  by  Chaldean  and  Egyptian  astronomers, 
and  was  further  developed  by  the  Greeks.  The  Arabian  scholars  of  the  Middle  Ages 
received  the  system  from  the  Greeks  and  handed  it  down,  with  a  few  modifications,  to 
European  astronomers.  Many  additions  and  alterations  were  made  by  astronomers  after 
the  sixteenth  century.  To-day  the  system  is  still  used,  but  only  for  purposes  of  notation, 
and  it  has  ceased  to  be  of  much  importance  in  the  strict  science  of  Astronomy. 

The  primitive  astronomers  adopted  the  pictorial   plan   of   distinguishing  the  stars. 

ived 
long 
ions. 

;  our 
ERRATA.  iefly 

tury 

PAGE  27.  Third  sentence  from  foot  should  read: 
Cassiopeia  is  above  the  pole  towards  the  right,  Ursa 
Major  low  in  the  sky  below  the  pole.  ' 

MAPS  I  AND  VI.  The  names  of  the  months  should 
be  changed  from  January  to  July,  from  February  to 

August,  and  so  on. 

was 

i  the 
Hist 

the 

3  US, 


but  in  Ptolemy's  and  in  subsequent  star  catalogues  the  position  of  each  star  is  given  in 
two  ways  :  (1)  by  its  place  in  the  constellation  figure,  and  (2)  by  the  system  of  longitude 
and  latitude  which  the  Greeks  had  adopted.  The  latter  system  enables  the  modern 
astronomer  to  identify  the  stars,  and  the  former  to  reproduce  the  outline  of  the  figure  with 
partial  success,  depending  upon  the  character  of  the  figure  and  upon  the  number  of  the 
stars  in  the  group.  Where  the  constellation  has  but  few  stars,  as  Canis  Minor,  which  has 
but  two  stars  in  Ptolemy's  catalogue,  the  reproduction  of  the  traditional  figure  is  very 
uncertain.  In  the  sixteenth  century,  the  German  astronomer  Heinfogel  secured  the 
assistance  of  the  artist  Albrecht  Diirer  in  reproducing  the  classic  figures,  and  his  highly 
embellished  drawings  formed  the  basis  of  the  figures  given  on  globes  and  atlases  until  the 
nineteenth  century.2  Present  atlases  either  omit  them  entirely,  or  give  them  in  merest 
outline  because  of  their  historical  interest  and  the  frequent  allusions  to  them  in  literature. 
They  have  ceased  to  have  any  use  in  modern  Astronomy. 

The  first  change  in  the  system  of  constellations  described  by  Ptolemy  was  made  by 
transferring  the  name  of  the  constellation  from  the  space  included  within  the  outlines  of 

1  Baily's  edition  iu  Memoirs  R.  A.  S.,  vol.  xiii.  *  Annales  Astronomiques,  I,  1878. 


iv  PREFACE. 

telescope,  and  which  crowd  an  atlas,  were  thus  omitted.  The  authority  for  the  magnitudes 
is  Harvard  Photometry,  and  its  extension  to  the  south  pole,  vols.  xiv,  xxiv,  and  xxxiv 
of  the  Annals  of  the  Astronomical  Observatory  of  Harvard  College. 

Argelander's  Uranometria  Nova  is  the  basis  of  the  boundaries  between  the  constella- 
tion areas,  and  also  of  the  outlines  of  the  historical  figures.  Behrmann's  extension  of  the 
constellations  to  the  southern  pole  on  Argelander's  plan  has  been  adopted  on  the  large 
maps,  and  Gould's  revision,  which  supersedes  Argelander's  south  of  10°  N.  declination,  for 
the  smaller  maps. 

The  designations  of  the  stars  follow  Argelander,  Behrmann,  Heis,  and  Gould.  The 
added  letters  of  Gould  are  used  except  where  his  revision  of  the  areas  places  a  star  in 
another  constellation. 

The  Milky  Way  is  drawn  only  approximately,  based  upon  the  drawings  of  Heis  and 
Gould. 

Th. 
of  Stan 

Th. 

variable 
Astrono 
The  doi 
Celestia 
tions  ai 
and  me 

Th 

been  m 
as  poss 

Ac 

educate 
and  Mr 

the  skL.  u*.  +.^.  ^.. -„ — . 

Poates. 


W1NSLOW   UPTON. 
BROWN  UNIVERSITY,  PROVIDENCE,  R.  I., 

June,  1896. 


EXPLANATORY    TEXT. 


THE    CONSTELLATIONS. 

THE  division  of  the  sky  into  constellations  is  the  oldest  part  of  the  science  of 
Astronomy.  It  was  begun  in  prehistoric  times  by  Chaldean  and  Egyptian  astronomers, 
and  was  further  developed  by  the  Greeks.  The  Arabian  scholars  of  the  Middle  Ages 
received  the  system  from  the  Greeks  and  handed  it  down,  with  a  few  modifications,  to 
European  astronomers.  Many  additions  and  alterations  were  made  by  astronomers  after 
the  sixteenth  century.  To-day  the  system  is  still  used,  but  only  for  purposes  of  notation, 
and  it  has  ceased  to  be  of  much  importance  in  the  strict  science  of  Astronomy. 

The  primitive  astronomers  adopted  the  pictorial  plan  of  distinguishing  the  stars. 
They  selected  from  the  heavens  prominent  groups  of  stars,  gave  to  them  names  derived 
from  natural  objects  or  from  their  mythology,  and  imagined  figures  to  be  drawn  among 
the  stars  to  represent  the  objects.  Thus  was  formed  the  ancient  system  of  constellations. 
Many  of  them  are  mentioned  by  early  writers  such  as  Homer,  Hesiod,  and  Aratus,  but  our 
knowledge  of  the  definite  location  of  the  groups  to  which  they  allude  is  derived  chiefly 
from  the  star  catalogue  of  the  Greek  astronomer  Ptolemy,  who  lived  in  the  second  century 
of  the  Christian  era.  This  star  catalogue 1  contains  1028  stars  and  is  made  up  of  the 
brighter  stars  visible  in  northern  latitudes.  It  groups  the  stars  into  forty-eight  constel- 
lations, which  include  926  of  the  whole  number  ;  the  others  are  mentioned  as  unclassified, 
and  are  given  as  additional  to  the  constellations  near  which  they  lie.  It  is  probable  that 
the  early  astronomers  did  not  intend  to  map  out  the  whole  sky  into  constellations,  but 
simply  to  select  the  prominent  groups  and  give  them  names  for  convenience  in  their  study. 
Astrology  furnished  the  motive  for  the  classification,  and  the  study  of  the  star  groups  was 
directed  to  the  determination,  if  possible,  of  the  influence  which  the  groups  had  upon  the 
earth  and  its  inhabitants.  Some  prominent  stars,  as  Arcturus,  were  in  the  unclassified  list 
and  not  in  any  constellation. 

The  individual  stars  were  named  from  their  positions  in  the  figures  which  the 
astronomers  drew  among  the  stars.  The  figures  themselves  have  not  come  down  to  us, 
but  in  Ptolemy's  and  in  subsequent  star  catalogues  the  position  of  each  star  is  given  in 
two  ways  :  (1)  by  its  place  in  the  constellation  figure,  and  (2)  by  the  system  of  longitude 
and  latitude  which  the  Greeks  had  adopted.  The  latter  system  enables  the  modern 
astronomer  to  identify  the  stars,  and  the  former  to  reproduce  the  outline  of  the  figure  with 
partial  success,  depending  upon  the  character  of  the  figure  and  upon  the  number  of  the 
stars  in  the  group.  Where  the  constellation  has  but  few  stars,  as  Canis  Minor,  which  has 
but  two  stars  in  Ptolemy's  catalogue,  the  reproduction  of  the  traditional  figure  is  very 
uncertain.  In  the  sixteenth  century,  the  German  astronomer  Heinfogel  secured  the 
assistance  of  the  artist  Albrecht  Diirer  in  reproducing  the  classic  figures,  and  his  highly 
embellished  drawings  formed  the  basis  of  the  figures  given  on  globes  and  atlases  until  the 
nineteenth  century.2  Present  atlases  either  omit  them  entirely,  or  give  them  in  merest 
outline  because  of  their  historical  interest  and  the  frequent  allusions  to  them  in  literature. 
They  have  ceased  to  have  any  use  in  modern  Astronomy. 

The  first  change  in  the  system  of  constellations  described  by  Ptolemy  was  made  by 
transferring  the  name  of  the  constellation  from  the  space  included  within  the  outlines  of 

1  Baily's  editiou  in  Memoirs  11.  A.  S.,  vol.  xiii.  »  Annales  Astronomiques,  I,  1878. 


2  EXPLANATORY  TEXT. 

the  figure  to  a  larger  space  in  the  sky,  within  which  the  figure  represented  by  the  name 
was  included.  Then  new  constellations  were  added  in  the  spaces  between  the  original 
groups,  with  the  design  of  covering  the  whole  sky  with  constellations.  The  new  constel- 
lations were  added  chiefly  by  astronomers  between  the  sixteenth  and  nineteenth  centuries, 
who  worked  independently  of  each  other.  As  a  result  there  was  no  agreement  either  in 
the  new  constellations  or  in  the  drawing  of  the  boundaries  between  adjacent  areas. 
To-day  there  is  still  disagreement  on  both  these  points ;  professional  astronomers  use 
different  designations  for  different  parts  of  the  sky,  and  star  atlases  are  not  in  harmony 
with  each  other,  especially  for  the  constellations  in  the  southern  hemisphere. 

The  ancient  system  of  the  constellations,  with  its  subsequent  additions,  survives  in 
modern  Astronomy  simply  as  a  means  of  subdividing  the  heavens  and  of  giving  names  to 
the  areas  thus  set  apart.  As  the  system  has  been  one  of  growth,  without  any  distinct 
plan  except  the  separation  of  prominent  groups  of  stars,  the  resulting  areas  are  of  various 
sizes  and  shapes.  In  a  few  cases  the  constellation  figures  crossed  each  other ;  the  best 
example  of  this  is  the  constellation  Serpens,  which  crossed  Ophiuchus,  the  figure  repre- 
senting the  serpent-carrier  holding  the  serpent  in  his  hands.  In  the  modern  atlas  the  area 
called  Serpens  is  divided  into  two  portions,  the  western  part,  marked  Caput,  and  the 
eastern,  Cauda,  to  correspond  with  the  positions  of  the  head  and  the  tail  of  the  serpent, 
and  the  area  named  Ophiuchus  extends  between  them.  In  some  cases,  moreover,  the  same 
star  was  in  more  than  one  figure.  Thus  the  northeastern  star  in  the  "  Square  of  Pegasus  " 
is  given  in  Bayer's  Atlas  both  as  8  Pegasi  and  also  as  a  Andromedce. 

Not  only  are  the  constellation  areas  of  various  sizes,  but  there  is  no  law  by  which  the 
boundaries  between  them  can  be  definitely  marked.  The  aim  of  the  compilers  of  atlases 
has  been  to  preserve  the  relation  of  the  areas  to  the  ancient  figures  as  far  as  possible. 
The  lack  of  concerted  action  has  necessarily  resulted  in  variety  of  treatment,  and  the 
matter  of  the  position  of  the  boundaries  is  of  such  minor  importance  in  modern  Astronomy 
that  little  interest  has  been  shown  in  the  various  schemes  proposed  for  rectifying  the 
boundaries.  A  radical  change  was  suggested  by  Sir  John  Herschel  in  1841 J ;  he  advocated 
a  complete  rearrangement  of  the  areas,  especially  of  those  in  the  southern  sky,  and 
proposed  that  each  area  be  made  a  quadrilateral  bounded  by  arcs  of  hour  circles  and 
parallels  of  declinations.  This  scheme  did  not  meet  with  favor,  but  it  was  revived  in  a 
modified  form  by  Dr.  Gould  in  1879,2  for  the  southern  constellations,  and  their  boundaries 
were  drawn  by  arcs  of  hour  circles  or  of  other  great  circles  and  parallels  of  declination. 
The  new  system  of  boundaries  was  made  to  depart  from  the  former  system  at  the  parallel 
10°  north  declination,  and  all  the  areas  south  of  this  region  were  bounded  by  definite  arcs 
on  the  above  plan  instead  of  by  the  irregular  lines  formerly  represented.  This  system 
is  coming  into  extensive  use,  as  it  is  employed  for  the  designation  of  variable  stars,  —  the 
only  growing  branch  of  modern  Astronomy  in  which  new  star  names  are  needed.  The  old 
areas  are,  however,  still  retained  by  some  astronomers  in  preference  to  the  revised  areas, 
and  stars  previously  named  on  the  old  plan,  which  under  the  new  plan  would  require 
renaming,  are  usually  mentioned  under  their  earlier  names. 

In  this  star  atlas  the  constellation  areas  are  named  and  their  boundaries  are  defined 
according  to  modern  usage ;  where  usage  varies  it  has  been  necessary  to  adopt  one  in 
preference  to  others.  The  Uranometry  of  Argelander,  published  in  1840,  extending  from 
the  north  pole  to  20°  or  30°  south  declination,  has  been  used  within  these  limits ;  and  its 
extension  to  the  south  pole,  executed  on  the  same  plan  by  Behrmann  in  1874,  has  been 
used  for  the  remainder  of  the  sky.  On  the  smaller  maps  containing  the  characteristic  star 

1  Memoirs  R.  A.  S.,  vol.  xii.  2  Uranometria  Argentina. 


THE    CONSTELLATIONS. 


groups  of  the  constellation  areas,  the  boundaries  adopted  have  been  those  of  Argelander 
from  the  north  pole  to  10°  north  declination,  and  the  reformed  boundaries  of  Gould  from 
that  parallel  southward. 

NAMES    OF    THE    CONSTELLATIONS. 

The  following  table  contains  the  names  of  the  constellations  included  in  this  atlas. 
They  are  given  in  their  Latin  form,  which  is  almost  universally  used,  with  accents  to 
assist  in  their  pronunciation.  The  genitive  case  of  the  name  is  also  appended,  as  it  is 
used  in  the  designations  of  the  brighter  stars  in  each  constellation.  Other  columns  contain 
the  meaning  of  each  word,  where  it  is  not  a  proper  name,  and  the  map  or  maps  upon 
which  it  is  found.  The  name  of  the  proposer  of  the  constellation  is  appended.  The  letter 
P  in  this  column  indicates  that  the  constellation  was  in  Ptolemy's  catalogue,  and  therefore 
belongs  to  the  list  of  constellations  used  by  the  ancient  astronomers.  The  twelve 
constellations  ascribed  to  Bayer  were  introduced  into  his  atlas  from  earlier  observations. 
The  origin  of  Crux  and  Cohimba  is  not  definitely  known,  and  some  of  Hevelius'  constel- 
lations were  in  use  before  his  time.  The  constellation  Argo  is  usually  subdivided  into  four 
parts,  named  Carina,  Malus,  Puppls,  and  Vela.  The  genitive  Argus  is  often  used  with 
stars  designated  by  Greek  letters,  but  the  modern  tendency  is  to  use  the  genitive  of  the 
name  of  the  subdivision  in  which  each  star  is  situated. 

TABLE  I.  —  THE   CONSTELLATIONS. 


No. 

NAME. 

GENITIVE. 

MEANING. 

MAP. 

PROPOSER. 

1 

Androm'-eda 

Androm'-edse 

I,  II 

P 

2 

Ant'-lia 

Ant'-lise 

Air  pump 

III 

Lacaille 

3 

A'-pus 

Ap'-odis 

Bird  of  Paradise 

VI 

Bayer 

4 

Aqua'-rius 

Aqua'-rii 

Water  carrier 

V 

P 

5 

A'-quila 

A'-quilse 

Eagle 

V 

P 

6 

A'-ra 

A'-rae 

Altar 

VI 

P 

- 

Ar'-go  (Navls) 

Ar'-gus 

Ship  Argo 

III,  VI 

P 

7 

A'-ries 

Ari'-etis 

Ram 

II 

P 

8 

Auri'-ga 

Auri'-gae 

Charioteer 

I,  II,  III 

P 

9 

Boo'-tes 

Boo'-tis 

Bear  keeper 

I,  IV 

P 

10 

Cae'-lum 

Cae'-li 

Sculptor's  chisel 

II,  VI 

Lacaille 

11 

Camelopar'-dalis 

Camelopar'-dalis 

Giraffe 

I 

Hevelius 

12 

Can'-cer 

Can'-cri 

Crab 

III 

P 

13 

Ca'-nes  Venat'-ici 

Ca'-numVenatico'-rum 

Hunting  dogs 

I,  IV 

Hevelius 

14 

Ca'-nis  Ma'-jor 

Ca'-nis  Majo'-ris 

Greater  dog 

III 

P 

15 

Ca'-nis  Mi'-nor 

Ca'-nis  Mino'-ris 

Lesser  dog 

III 

P 

16 

Capricor'-nus 

Capricor'-ni 

Goat 

V 

P 

17 

Cari'-na 

Cari'-nse 

Keel(of  ship  Argo) 

VI 

-r 

18 

Cassiope-ia 

Cassiope'-ise 

I 

P 

19 

Centau'-rus 

Centau'-ri 

Centaur 

IV,  VI 

P 

20 

Ce'-pheus 

Ce'-phei 

I 

P 

21 

Ce'-tus 

Ce'-ti 

Whale 

II 

P 

22 

Chamse'-leon 

Chamaeleon'-tis 

Chamaeleon 

VI 

Bayer 

23 

Cir'-cinus 

Cir'-cini 

Pair  of  compasses 

VI 

Lacaille 

24 

Colum'-ba 

Colum'-bae 

Dove 

II,  VI 

— 

25 

Co'-ma  Bereni'-ces 

Co'-mse  Bereni'-ces 

Berenice's  hair 

IV 

Tycho  Brahe 

26 

Coro'-na  Austra'-lis 

Coro'-nee  Austra'-lis 

Southern  crown 

V,  VI 

P 

27 

Coro'-na  Borea'-lis 

Coro'-nse  Borea'-lis 

Northern  crown 

IV 

P 

28 

Cor'-vus 

Cor'-vi 

Crow 

IV 

P 

29 

Cra'-ter 

C  rate  -r  is 

Cup 

III 

P 

30 

Crux 

Cru'-cis 

Cross 

VI 

— 

31 

Cyg'-nus 

Cyg'-ni 

Swan 

I,  V 

P 

32 

Delphi'-nus 

Delplii'-ni 

Dolphin 

V 

P 

EXPLANATORY  TEXT. 


No. 

NAME. 

GENITIVE. 

MEANING. 

MAP. 

PROPOSER. 

33 

Dora'-do 

Dora'-dus 

Sword  fish 

VI 

Bayer 

34 

Dra'-co 

Draco  '-iris 

Dragon 

I 

P 

35 

Equu'-leus 

Equu'-lei 

Little  horse 

V 

P 

36 

Erid'-anus 

Erid'-ani 

River  Po 

II,  VI 

P 

37 

For'-nax  (chemica) 

Forna'-cis 

Furnace 

II 

Lacaille 

38 

Gem'-ini 

Gemino'-rum 

Twins 

III 

P 

39 

Grus 

Gru'-is 

Crane 

V,  VI 

Bayer 

40 

Her'-cules 

Her'-culis 

I,  IV 

P 

41 

Horolo'-gium 

Horolo'-gii 

Clock 

II,  VI 

Lacaille 

42 

Hy'-dra 

Hy'-dree 

Snake 

III,  IV 

P 

43 

Hy'-drus 

Hy'-dri 

Watersnake 

VI 

Bayer 

44 

In'-dus 

In'-di 

Indian 

VI 

Bayer 

45 

Lacer'-ta 

Lacer'-tae 

Lizard 

i,v 

Hevelius 

46 

Le'-o 

Leo'-nis 

Lion 

III 

P 

47 

Le'-o  Mi'-nor 

Leo'-nis  Mino'-ris 

Lesser  lion 

III 

Hevelius 

48 

Le'-pus 

Lep'-oris 

Hare 

II 

P 

49 

Li'-bra 

Li'-brae 

Balance 

IV 

P 

50 

Lu'-pus 

Lu'-pi 

Wolf 

IV,  VI 

P 

51 

Lynx 

Lyn'-cis 

Lynx 

I,  III 

Hevelius 

52 

Ly'-ra 

Ly'rse 

Harp 

i,v 

P 

53 

Ma'-lus 

Ma'-li 

Mast(ofshipArgo) 

III 

— 

54 

Men'-sa(Mons  Mensse) 

Men'-sae 

Table  (mountain) 

VI 

Lacaille 

55 

Microsco'-pium 

Microsco'-pii 

Microscope 

V 

Lacaille 

56 

Monoc'-eros 

Monocero'-tis 

Unicorn 

III 

Hevelius 

57 

Mus'-ca 

Mus'-cse 

Fly 

VI 

Bayer 

58 

Nor'-ma 

Nor'-mae 

Rule 

IV,  VI 

Lacaille 

59 

Oc'-tans 

Octan'-tis 

Octant 

VI 

Lacaille 

60 

Ophiu'-chus 

Ophiu'-chi 

Serpent  carrier 

IV,  V 

P 

61 

Ori'-on 

Orio'-nis 

II,  III 

P 

62 

Pa'-vo 

Pavo'-nis 

Peacock 

VI 

Bayer 

63 

Peg'-asus 

Peg'-asi 

Winged  horse 

V 

P 

64 

Per'-seus 

Per'-sei 

I,  II 

P 

65 

Phoe'-nix 

Phceni'-cis 

Phosnix 

II,  VI 

Bayer 

66 

Pic-tor  (Equuleus  Pic- 

Picto'-ris 

Painter's  easel 

VI 

Lacaille 

toris) 

67 

Pis'-ces 

Pis'-cium 

Fishes 

II,  V 

P 

68 

Pis'-cis  Austra'-lis 

Pis'-cis  Austra'-lis 

Southern  fish 

V 

P 

69 

Pup  '-pis 

Pup  '-pis 

Stern  (of  ship  Argo) 

III,  VI 

— 

70 

Retic'-ulum 

Retic'-uli 

Net 

VI 

Lacaille 

71 

Sagit'-ta 

Sagit-tae 

Arrow 

V 

P 

72 

Sagitta'-rius 

Sagitta'-rii 

Archer 

V,  VI 

P 

73 

Scor'-pius 

Scor'-pii 

Scorpion 

IV,  VI 

P 

74 

Sculp'-tor    (Apparatus 

Sculpto'-ris 

Sculptor's  appara- 

1I,V,VI 

Lacaille 

Sculptoris) 

tus 

75 

Scu'-tum  (Sobiesii) 

Scu'-ti 

Shield  of  Sobieski 

V 

Hevelius 

76 

Ser'-pens 

Serpen'-tis 

Serpent 

IV,  V 

P 

77 

Sex'-tans 

Sextan  '-tis 

Sextant 

III 

Hevelius 

78 

Tau'-rus 

Tau'-ri 

Bull 

II 

P 

79 

Telesco'-pium 

Telesco'-pii 

Telescope 

VI 

Lacaille 

80 

Trian'-gulum 

Trian'-guli 

Triangle 

II 

P 

81 

Trian'-gulumAustra'-le 

Trian'-guli  Austra'-lis 

Southern  triangle 

VI 

Bayer 

82 

Tuca'-na 

Tuca'-nae 

American  goose 

VI 

Bayer 

83 

Ur'-sa  Ma'-jor 

Ursae  Majo'-ris 

Greater  bear 

I,  III 

P 

84 

Ur'-sa  Mi'-nor 

Ursae  Mino'-ris 

Lesser  bear 

I 

P 

85 

Ve'-la 

Velo'-rum 

Sails  (of  ship  Argo) 

III,  VI 

— 

86 

Vir'-go 

Vir'-ginis 

Virgin 

IV 

P 

87 

Vo'-lans  (Piscis  volans) 

Volan'-tis 

Flying  fish 

VI 

Bayer 

88 

Vulpec'-ula    (cum    an- 

Vulpec'-ulae 

Fox  with  goose 

V 

Hevelius 

sere) 

DESIGNATIONS   OF  STARS.  5 

The  above  list  of  constellations  includes  all  which  are  generally  accepted  at  the 
present  time.  The  total  number  is  eighty-five  if  Argo  is  considered  as  one  constellation, 
or  eighty-eight  if  each  of  its  subdivisions  is  reckoned  as  a  separate  constellation.  There 
are  many  other  constellations  which  have  been  proposed  by  eminent  astronomers  and  used 
to  a  limited  extent.1  Thus  Bode  added  nine  constellations,  one  of  which,  Machina  Electrica, 
was  inserted  by  Argelander  in  his  supplementary  map  of  the  southern  heavens.  Lacaille 
substituted  for  Malm  the  name  Pyxis  (genitive  Pyx-idos]  mariner's  compass,  and  this  is 
extensively  used  to-day.  The  constellation  Antinous,  ascribed  to  Tycho  Brahe,  is  included 
in  Aquila;  Taurus  Poniatowskii,  ascribed  to  Poczobut,  is  included  in  Ophiuchus  and  Serpens. 
The  constellation  Libra,  which  is  the  only  one  of  the  twelve  zodiacal  groups  not  bearing  the 
name  of  an  animal  as  the  derivation  of  the  word  zodiac  implies,  is  in  Ptolemy's  catalogue 
called  Clatvs  (of  the  Scorpion).  Scutum  is  sometimes  called  by  its  Greek  equivalent  Clypeus. 


DESIGNATIONS    OP    STARS. 

Individual  stars  have  been  designated  by  astronomers  in  several  different  ways : 

1.  By  their  position  in  the  constellation  figure.     This  method  is  now  entirely  obsolete. 

2.  By  individual  names.     The  names  have  come  down  to  us  chiefly  from  classical  and 
mediaeval  times,  and  are  either  of  Latin  form  or  in  a  corrupted  form  of  the  Arabic  desig- 
nation of  the  star  in  its  constellation  figure.     Very  few  of  the  names  are  now  used.     The 
method  is  nearly  obsolete,  surviving  in  only  a  few  of  the  brightest  stars. 

3.  By  Greek  or  Roman  letters,  followed  by  the  name  of  the  constellation  in  the  genitive 
case  of  its  Latin  form.     This  method  was  introduced  by  Bayer  early  in  the  seventeenth 
century,  who  lettered  the  leading  stars  in  each  constellation  of  the  northern  heavens,  using 
the  Greek  alphabet,  and  if  the  number  of  stars  in  the  constellation  exceeded  the  number  of 
Greek  letters,  using  Roman  letters.     The  stars  were  lettered  in  the  order  of  their  bright- 
ness as  far  as  the  several  magnitudes  were  concerned,  but  no  attempt  seems  to  have  been 
made  to  distinguish  between  the  stars  of  any  given  magnitude.     Later  astronomers  have 
adopted  the  same  system  in  constellations  not  in  Bayer's  list.     Nearly  all  of  the  stars  readily 
visible  to  the  naked  eye  are  designated  by  letters  on  this  plan,  and  astronomers  prefer  this 
system  to  any  of  the  others. 

4.  By  Arabic  numbers,  followed  by  the  name  of  the  constellation  in  the  genitive  case 
of  its  Latin  form.     This  method  was  introduced  by  Flamsteed  in  the  seventeenth  century, 
whose  numbers  follow  the  order  of  the  stars  in  right  ascension.     Other  astronomers  used 
the  same  plan.     This  method  is  used  by  astronomers  for  stars  not  already  lettered  on  Bayer's 
plan.     Where  both  letters  and  numbers  have  been  given,  the  letters  are  preferred. 

5.  By  the  current  number  in  any  well-known  modern  star  catalogue.     This  method  is 
used  when  the  star  has  neither  letter  nor  number. 

6.  By  the  position  of  the  star  in  the  sky,  the  system  corresponding  to  longitude  and 
latitude  on  the  earth.     On  the  celestial  sphere,  right  ascension  and  declination  are  the  terms 
employed.     This  method  is  used  for  uncatalogued  stars. 

The  brightest  stars  have  designations  in  all  six  of  the  above  ways.  Thus  the  bright 
star  which  is  near  the  northern  celestial  pole  was  designated  (1)  the  star  at  the  end  of  the 
tail  of  the  lesser  bear,  (2)  Gjedi,  Polaris,  Cynosura,  Alruccabah,  (3)  a  Ursce  Minoris,  (4)  1 
Ursce  Minoris.  It  might  also  be  referred  to  under  (5)  as  B.  A.  C.  360,  the  current  number 

1  See  Chambers'  Astronomy,  vol.  iii,  chap,  vii,  ed.  1890,  and  Burritt's  Geography  of  the  Heavens. 


EXPLANATORY  TEXT. 


in  the  British  Association  Catalogue  (or  by  a  similar  designation  in  any  other  catalogue  in 
which  it  occurs),  and  under  (6)  as  in  right  ascension  1  h.  23  min.,  declination  +  88°  46'. 
Of  these  names,  a  Ursce  Minoris  is  preferred,  but  Polaris  is  still  in  frequent  use ;  all  the 
other  designations  are  obsolete. 

The  majority  of  stars  readily  visible  to  the  naked  eye  are  therefore  usually  designated 
by  letter  and  name  of  constellation  area ;  a  large  number,  especially  of  the  fainter  ones,  are 
called  by  a  number  with  the  name  of  the  constellation  area ;  a  few  have  individual  names. 
The  faintest  stars  visible  without  a  telescope,  and  all  requiring  its  aid,  are  referred  to  by 
their  numbers  in  star  catalogues,  or  by  their  right  ascensions  and  declinations. 

In  this  atlas,  following  present  usage,  the  individual  stars  are  designated  by  a  letter 
or  by  a  number,  if  such  letter  or  number  is  in  use.  The  individual  names  of  stars  of  the 
first  magnitude,  and  of  a  few  others  which  are  extensively  used,  are  also  given  upon  the 
maps.  In  referring  to  the  stars,  the  letter  or  number  should  be  used  with  the  genitive 
of  the  name  of  the  constellation  given  in  Table  I,  as  a  Herculis,  61  Cygni.  The  Greek 
alphabet  is  here  given. 

GREEK  ALPHABET. 


a 

alpha 

V 

nu 

P 

beta 

1 

xi 

V 

gamma 

o 

om'-icron 

5 

delta 

IT 

Pi 

£ 

eps'-ilon 

P 

rho 

£ 

zeta 

<r 

sigma 

1 

eta 

T 

tau 

e 

theta 

V 

u'-psilon 

i 

iota 

+ 

phi 

K 

kappa 

X 

chi 

X 

lambda 

* 

psi 

K- 

mu 

CO 

o'-mega 

INDIVIDUAL   STAB,  NAMES. 

Individual  names  have  been  given  to  several  hundred  of  the  stars.  Some  were  assigned 
by  the  Chaldean  astronomers,1  but  the  earliest  which  are  still  used  date  from  classic  times 
and  are  given  in  their  Latin  form.  The  Arabian  astronomers  added  many  others,  the  name 
usually  describing  the  position  of  the  star  in  the  constellation  figure.  Individual  names  of 
the  stars  are  now  rarely  employed ;  only  those  of  the  brightest  stars  survive,  and  even  for 
them  the  designation  by  letters  is  usually  preferred.  In  this  atlas,  the  individual  names 
of  stars  of  the  first  magnitude  are  given,  with  a  few  others,  as  Algol,  which  are  in  general 
use.  The  following  table  contains  names  which  are  sometimes  used,  together  with  the 
preferred  designation  by  letter  with  the  name  of  the  constellation,  and  also  the  meaning  of 
the  word.  The  pronunciation  of  the  words  derived  from  the  Arabic  is  a  matter  of  uncer- 
tainty because  they  appear  in  a  corrupted  form  ;  the  spelling  itself  is  often  variously  given. 
Thus,  Betelgeuse  is  variously  written  Betelguese,  Beteigeuze,  Betelgeux,  Betelgeuxe,  and  is 
corrupted  from  ibt  al  Jauza.2  Its  pronunciation  is  a  matter  of  personal  preference. 


1  Epping,  Astronomisches  aus  Babylon. 
a  Higgins,  Arabic  Names  of  the  Stars. 


DESIGNATIONS   OF   STARS. 


TABLE  II.  —  INDIVIDUAL  STAR  NAMES. 


NAME. 

OTHER  DESIGNATION. 

MEANING. 

Acliernar 

a      Eridani 

The  end  of  the  river 

Alcor 

g      Ursae  Majoris 

The  near  one 

Aldebaran 

a      Tauri 

The  eye  of  the  bull 

Alderamin 

a      Cephei 

The  arm 

Alfard 

a      Hydrae 

The  solitary 

Algenib 

y      Pegasi 

The  side 

Algol 

ft     Persei 

The  monster 

Alcaid 

i\      Ursae  Majoris 

The  chief 

Alioth 

£      Ursae  Majoris 

The  tail-sheep 

Almach 

y      Andromedae 

The  bound  one 

Alphecca 

a      Corona  Borealis 

The  broken  dish 

Alpheratz 

a      Andromedae 

The  horse 

Alruccabah 

a      Ursae  Miuoris 

The  chariot 

Altai  r 

a      Aquilae 

The  bird 

Antares 

a      Scorpii 

Equal  to  Mars  (red  color) 

Arcturus 

a      Bootis 

Guardian  of  the  bear 

Arided 

a      Cygni 

The  tail  piece 

Bellatrix 

y      Orionis 

Female  warrior 

Betelgeuse 

a      Orionis 

Armpit  of  the  giant 

Canopus 

a      Argus 

(Proper  name  —  Menelaus'  pilot) 

Capella 

a      Aurigee 

A  little  she-goat 

Caph 

ft     Cassiopeiae 

Palm  of  the  hand 

Castor 

a      Geminorum 

(Proper  name) 

Cynosura 

a       Ursae  Minoris 

Dog's  tail 

Deneb  kaitos 

£     Ceti 

Tail  of  the  whale 

Denebola 

ft     Leoiiis 

Tail  of  the  lion 

Dubhe 

a      Ursse  Majoris 

She-bear 

Fomalhaut 

a      Piscis  Australis 

Mouth  of  the  fish 

Hyades 

Group  in  Taurus 

From  Greek  —  to  rain 

Kochab 

ft     Ursse  Minoris 

Star 

Markab 

a      Pegasi 

Saddle 

Megrez 

8      Ursae  Majoris 

Rump 

Menkar 

a      Ceti 

Nostril 

Merak 

ft     Ursae  Majoris 

Flank 

Mira 

o      Ceti 

Wonderful 

Mirach 

ft     Andromedae 

Loins 

Mirfak 

a      Persei 

Elbow 

Mizar 

£       Ursae  Majoris 

A  girdle 

Phecda 

y      Ursae  Majoris 

Thigh 

Pleiades 

From  Greek  —  to  sail 

Alcyone 

77      Tauri 

~ 

Asterope 

21,  22  Tauri 

Atlas 

27     Tauri 

Celieno 

g      Tauri 

Atlas,  the  nymph  Pleione, 

Electra 

17     Tauri 

and  their  seven 

Maia 

20     Tauri 

daughters 

Merope 

23     Tauri 

Pleione 

28     Tauri 

Taygeta 

19     Tauri 

Polaris 

a      Ursae  Minoris 

Pole  star 

Pollux 

ft      Geminorum 

(Proper  name) 

Praesepe 

Cluster  in  Cancer 

Crib  or  manger 

Procyon 

a      Canis  Minoris 

Precursor  dog 

Ras-Alhague 

a      Opliiuclii 

Head  of  the  serpent  charmer 

Ras-Algethi 

a      Herculis 

Head  of  the  kneeler 

Regulus 

a      Leonis 

Chief 

Rigel 

ft     Orionis 

Foot 

Scheat 

ft     Pegasi 

Foreleg 

Schedar 

a      Cassiopeiae 

Breast 

Sirius 

a      Canis  Majoris 

From  Siris  —  the  Nile 

Spica 

a      Virginis 

An  ear  of  wheat 

Thuban 

a      Draconis 

A  dragon 

Vega 

a      Lyrae 

Falling  (eagle) 

8  EXPLANATORY    TEXT. 


BRIGHTNESS   OF  THE   STARS. 

In  Ptolemy's  catalogue  the  stars  were  divided  into  six  classes,  according  to  their 
brightness.  The  word  "  magnitude  "  was  used  as  the  equivalent  of  brightness,  and  the 
first  six  letters  of  the  Greek  alphabet  were  employed  in  their  order  to  distinguish  the 
several  classes.  The  word  "magnitude"  is  still  used  in  this  erroneous  sense,  though 
the  brightness  of  a  star,  as  we  see  it,  depends  upon  its  distance  and  intrinsic  light-power  as 
well  as  upon  its  size.  Stars  visible  to  the  naked  eye  are  still  subdivided  into  six  "  magni- 
tudes," and  the  fainter  stars  revealed  by  the  telescope  are  similarly  grouped  into  those  of 
the  seventh  magnitude,  eighth  magnitude,  etc.,  by  an  extension  of  the  same  principle. 

This  rough  classification  has  been  made  the  basis  of  the  more  accurate  classification 
which  modern  astronomy  requires.  It  was  found  that  the  several  orders  of  magnitude 
estimated  by  various  astronomers  differed  by  a  light  ratio  very  nearly  2|.  That  is,  a  star 
of  the  third  magnitude  gives  2^  times  as  much  light  as  one  of  the  fourth  magnitude ;  one 
of  the  fourth  1\  times  as  much  light  as  one  of  the  fifth  magnitude,  and  so  on.  Modern 
photometric  researches  are  made  upon  the  assumption  of  this  constant  light  ratio  (the 
adopted  ratio  is  2.512  or  ^/Too)-  In  this  way  the  modern  treatment  of  the  subject  of  the 
brightness  of  the  stars  is  simply  a  refinement  in  method,  but  with  no  change  of  plan  from 
that  followed  by  the  earlier  astronomers  and  their  successors.  Since  the  stars  are  of  every 
degree  of  brightness,  the  gradations  are  expressed  upon  a  numerical  scale,  with  fractions 
of  a  magnitude  expressed  decimally.  Thus,  61  Cygni,  which  is  near  the  dividing  line 
between  a  star  of  the  fifth  and  one  of  the  sixth  magnitude,  is  now  given  as  of  the  5.6 
magnitude. 

The  modern  system  of  designating  the  brightness  of  stars  is,  then,  to  express  it  numer- 
ically, upon  a  scale  agreeing  in  general  with  the  "magnitudes  "  of  the  earlier  astronomers. 
First  magnitude  stars  are  those  between  0.5  and  1.5  on  the  photometric  scale,  second 
magnitude  stars  are  those  between  1.5  and  2.5,  third  magnitude  stars  those  between  2.5 
and  3.5,  and  so  on.  The  only  important  departure  from  the  earlier  system  is  in  the  case  of 
the  twenty  brightest  stars  of  the  sky.  The  ancients  included  in  the  group  of  stars  which 
they  called  those  of  the  first  magnitude  all  the  brightest  stars,  ranging  from  a  Cam's 
Majoris,  or  Sirius,  to  a  Leonis,  or  Eegulus.  But  the  former  is  thirteen  times  as  bright  as 
the  latter,  and  therefore  should  be  in  a  class  nearly  three  magnitudes  brighter.  The 
first  magnitude  stars,  though  few  in  number,  really  belong  in  several  classes.  The  actual 
measurement  of  the  amount  of  light  given  by  the  twenty  brightest  stars  shows  that  eleven 
of  them  are  between  0.5  and  1.5  magnituda,  and  hence  of  the  first  magnitude  ;  that  seven 
should  be  placed  in  the  next  brighter  division,  and  hence  are  of  the  zero  magnitude,  and 
that  two  belong  in  a  class  still  brighter.  As  the  scale  has  run  out,  the  brightness  of  these 
two  stars  is  expressed  with  a  minus  sign  before  it.^  The  following  table  contains  the 
list  of  stars  generally  known  as  first  magnitude  stars,  rearranged  according  to  the  modern 
scale.1 

1  Annals  Observatory  of  Harvard  College,  vol.  xviii,  no.  1. 


STAR   SYMBOLS. 


9 


TABLE  III.  —  STARS  OF  THE  FIRST  MAGNITUDE,  REARRANGED. 


A.     STABS  BRIGHTER  THAN  0  MAGNITUDE. 

C.     STARS  OF  1ST  MAGNITUDE. 

NAME. 

MAONI- 

MAP. 

NAME. 

MAGNI- 

MAP. 

TUDE. 

a  Canis  Majoris  (Sirius) 

14 

II,  III 

a  Tauri  (Aldebaran) 

1.0 

II 

a  Argus  (Canopus) 

—  0.8 

VI 

a  Orionis  (Betelyeuse) 

0.9 

II,  III 

B.     STARS  OF  0  MAGNITUDE. 

ft  Gerninorum  (Pollux) 
a  Leonis  (Regulus) 

1.2 

1.3 

III 

III 

a  Eridani  (Achernar) 

0.4 

VI 

a  Crucis 

1.0 

VI 

a.  Aurigze  (Capellii) 

0.1 

I 

a  Virginia  (Spica) 

1.1 

IV 

/J  Oriouis  (Rigel) 

0.3 

II 

/3  Centauri 

0.7 

VI 

a.  Canis  Minoris  (Procyoii) 

0.5 

III 

a  Scorpii  (Antares) 

1.2 

IV 

a  Bootis  (Arcturus) 

0.2 

IV 

a  Aquilse  (Altair) 

0.9 

V 

a  Centauri 

0.2 

VI 

a  Cygni  (Deneb  or  Arided) 

1.4 

I 

a  Lyrse  (  Vega) 

0.2 

IV,  V 

a.  PiscisAustralis(/b?»a7/t«M<) 

1.3 

V 

STAR  SYMBOLS. 

In  this  star  atlas,  symbols  agreeing  with  those  used  by  Argelander  and  others  have 
been  adopted  to  express  the  several  magnitudes.  Stars  are  charted  down  to  the  6.0  magni- 
tude, which  includes  all  readily  visible  to  the  naked  eye.  The  largest  symbol  is  used  for 
the  nine  stars  which  are  brighter  than  the  first  magnitude,  the  next  for  those  of  the  first 
magnitude,  that  is,  0.5  to  1.5  on  the  photometric  scale,  the  next  symbol  for  those  of  the 
second  magnitude,  that  is,  1.5  to  2.5  on  the  photometric  scale,  and  so  on.  In  the  smaller 
maps  the  magnitudes  are  expressed  by  circles  of  progressive  sizes,  as  there  stated. 


STAR  CLUSTERS  AND  NEBULA. 

In  this  atlas  are  indicated  the  star  clusters  and  nebulae  which  can  be  seen  in  small 
telescopes.  It  is  not  always  possible  to  distinguish  between  nebulous-appearing  objects 
which  may  be  true  nebulae,  that  is,  of  gaseous  constitution,  and  those  which  are  clusters  of 
separate  stars.  Sometimes,  too,  the  same  object  is  a  cluster  and  nebula  combined.  The 
atlas  has  two  different  symbols,  but  there  is  sometimes  doubt  as  to  which  should  be 
employed. 

The  study  of  nebulae  requires,  except  in  a  few  instances,  telescopes  whose  apertures 
are  at  least  twelve  inches ;  in  smaller  instruments  they  appear  simply  as  faint  patches  of 
light. 

The  following  tables  contain  the  principal  clusters  and  nebulae  which  are  charted  on 
the  maps,  their  right  ascensions,  declinations,  and  the  maps  on  which  they  may  be  found. 
Condensed  descriptions,  usually  following  those  in  Dreyer's  Catalogue  of  Nebuloa  and 
Clusters 1  are  appended.  To  the  list  of  nebulae  are  also  appended  a  few  notes  regarding  the 
most  important  ones.  The  numbers  in  the  first  column  are  those  in  Dreyer's  Cata- 
logue, the  letters  N.  G.  C.  standing  for  New  General  Catalogue. 


Memoirs  R.  A.  S.,  vol.  xlix. 


10 


EXPLANATORY   TEXT. 


TABLE  IV.  —  STAR  CLUSTERS. 


No. 
N.  G.  C. 

RIGHT 
ASCENSION. 

DECLINATION. 

MAP. 

DESCRIPTION. 

104 

Oh-  20m. 

-72°    38' 

VI 

very  bright,  very  large,  globular 

129 

0     24 

59     40 

I 

very  large,  stars  9th  to  13th  magnitude 

188 

0     35 

84     47 

I 

very  large,  150-200  stars 

225 

0     37 

61     15 

I 

large,  stars  9th  to  10th  magnitude 

288 

0     48 

-27       8 

n,  v 

bright,  large,  globular 

362 

0     59 

-71     23 

VI 

very  bright,  very  large,  globular 

663 

1     39 

60     44 

I 

bright,  large 

752 

1     52 

37     11 

II 

exceedingly  large,  visible  to  eye  as  nebulous  star 

869 

2     12 

56     41 

I 

exceedingly  large,  stars  7th  to  14th  magnitude 

884 

2     15 

56     39 

I 

very  large,  very  many  stars 

1039 

2     36 

42     21 

I,  II 

bright,  very  large 

1245 

3       8 

46     52 

I,  II 

quite  large,  rich  in  faint  stars 

1291 

3     14 

-41     28 

11,  VI 

very  bright,  quite  large,  globular 

1387 

3     33 

-35     51 

II 

very  bright,  quite  large,  globular 

1399    ' 

3     35 

—  35    47 

II 

very  bright,  quite  large,  globular,  easily  revolved 

1436 

3     40 

-36     26 

II 

very  bright,  globular 

1528 

4       8 

50     59 

I 

bright,  many  stars 

1787 

5       0 

—  65     59 

VI 

very  large,  many  stars 

1850 

5      9 

—  68     53 

VI 

very  bright,  large,  globular,  easily  resolved 

1851 

5     11 

-40       9 

II,  VI 

very  bright,  very  large,  globular,  easily  resolved 

1855 

5     10 

—  68    58 

VI 

very  bright,  large 

1857 

5     13 

39     14 

II 

somewhat  compressed 

1904 

5     20 

-24    37 

II,  III 

quite  large,  very  many  stars,  globular,  easily  resolved 

1912 

5     22 

35    45 

II,  III 

bright,  very  large,  very  many  stars 

1960 

5     29 

34      5 

II,  III 

bright,  very  large,  very  many  stars 

2015 

5     33 

-69     20 

VI 

very  large,  many  stars 

2027 

5    35 

-66    59 

VI 

very  large,  stars  9th  to  llth  magnitude 

2034 

5    36 

-66     57 

VI 

very  large,  many  stars 

2099 

5     46 

32     31 

II,  III 

quite  compressed,  exceedingly  large  number  of  stars 

2118 

5    48 

-69     10 

VI 

very  bright,  globular 

2164 

5     59 

—  68     31 

VI 

very  bright,  globular,  easily  resolved 

2168 

6       3 

24     21 

II,  III 

very  large,  many  stars 

2244 

6     27 

4     56 

II,  III 

about  12  Monocerotis 

2287 

6     43 

—  20     38 

II,  III 

very  large,  bright 

2301 

6     47 

0     35 

III 

large,  many  stars 

2323 

6     58 

-   8     12 

III 

very  large,  many  stars 

2360 

7     13 

-15     27 

III 

very  large,  many  stars 

2422 

7     32 

-14     16 

III 

bright,  very  large,  many  stars 

2437 

7     37 

-14     35 

111 

very  bright,  very  large,  very  many  stars 

2447 

7     40 

—  23     38 

III 

large,  stars  8th  to  13th  magnitude 

2451 

7     42 

-37     44 

III 

exceedingly  large,  about  c  Puppis 

2477 

7     49 

—  38     17 

III 

bright,  large,  many  stars 

2506 

7     55 

-10    21 

III 

quite  large,  very  rich  in  faint  stars 

2516 

7     57 

-60    36 

VI 

very  bright,  very  large,  stars  7th  to  13th  magnitude 

2539 

8      6 

—  12     32 

III 

very  large,  many  stars 

2547 

8      8 

-48     58 

VI 

bright,  large 

2632 

8    34 

20    20 

III 

Prcesepe  in  Cancer,  visible  to  the  naked  eye 

2682 

8    46 

12     11 

III 

very  bright,  very  large,exceedinglylarge  number  of  stars 

2808 

9     10 

-64     27 

VI 

very  large,  very  many  stars,  globular 

2932 

9     32 

—  46     30 

VI 

exceedingly  large,  very  many  stars 

3114 

9     59 

-59     38 

VI 

exceedingly  large,  stars  9th  to  14th  magnitude 

3532 

11       2 

-58       8 

VI 

exceedingly  large,  round 

3766 

11     32 

-61       2 

VI 

very  large,  150-200  stars 

4147 

12      5 

19       6 

III,  IV 

very  bright,  quite  large,  globular,  easily  resolved 

4755 

12    48 

-59    48 

VI 

very  large,  about  K  Crucis 

5024 

13      8 

18     42 

IV 

bright,  very  compressed,  globular 

5045 

13     10 

-62     53 

VI 

very  large,  very  many  stars 

5139 

13    21 

-46     47 

VI 

exceedingly  brilliant,  o>  Centauri,  visible  to  naked  eye 

5272 

13    38 

28     53 

IV 

very  bright,  very  large,  vast  number  of  stars 

STAR    CLUSTERS  AND  NEBULA. 


11 


No. 
N.  G.  C. 

RIGHT 
ASCENSION. 

DECLINATION. 

MAP. 

DESCRIPTION. 

5822 

14  h.  58  m. 

-53°  57' 

VI 

very  large,  many  stars 

5904 

15     13 

2     27 

IV 

very  bright,  large,  many  stars 

5986 

15     40 

-37     27 

IV 

very  bright,  large 

6067 

16       5 

—  53     57 

VI 

very  bright,  very  large,  very  many  stars 

6087 

16     11 

-57     39 

VI 

bright,  large,  stars  7th  to  10th  magnitude 

6093 

16     11 

-22     44 

IV 

very  bright,  large,  globular,  easily  resolved 

6169 

16     27 

-43     50 

IV,  VI 

about  /j.  Normce 

6171 

16     27 

-12     50 

IV 

large,  very  many  stars,  easily  resolved 

6205 

16     38 

36     39 

IV 

very  bright,  vast  number  of  faint  stars 

6218 

16     42 

—   1     46 

IV 

very  bright,  very  large,  easily  resolved 

6227 

16     45 

-41       3 

IV,  VI 

exceedingly  large,  very  rich  in  stars 

6254 

16     52 

—   3     57 

IV 

bright,  very  large,  easily  resolved 

6259 

16     54 

-44     31 

IV,  VI 

bright,  very  large,  very  many  stars 

6266 

16     55 

-29     58 

IV 

very  bright,  large,  globular,  easily  resolved 

6333 

17     13 

-18     25 

IV 

bright,  large,  globular,  easily  resolved 

6341 

17     14 

43     15 

I,  IV 

very  bright,  very  large,  globular,  easily  resolved 

6402 

17     32 

-   3     11 

IV,  V 

bright,  very  large,  very  many  stars,  globular 

6444 

17     44 

-34     50 

IV,  V 

very  large,  very  many  stars 

6475 

17     48 

-34     47 

IV,  V 

very  bright,  many  stars 

6494 

17     51 

-19       0 

IV,  V 

bright,  very  large,  many  stars 

6523 

17     57 

-24     23 

IV,  V 

very  bright,  very  large 

6568 

18       7 

-21     37 

IV,  V 

very  large,  stars  of  10th  magnitude 

6603 

18     13 

-18     27 

IV,  V 

very  many  stars,  visible  to  naked  eye 

6611 

18     13 

-13     49 

IV,  V 

many  stars 

6626 

IS     18 

-24     55 

IV,  V 

very  bright,  large,  easily  resolved 

6633 

18     23 

6     29 

IV,  V 

many  bright  stars,  visible  to  naked  eye 

6656 

18     30 

-23     59 

IV,  V 

very  bright,  very  large,  very  many  stars,  globular 

6705 

18     46 

—   6     23 

V 

very  bright,  large 

6752 

19       2 

-60       8 

VI 

bright,  very  large,  easily  resolved 

6838 

19     49 

18     31 

V 

very  large,  very  many  stars 

6866 

20       0 

43    43 

I,  V 

large,  very  many  stars 

6885 

20       8 

26     10 

V 

very  bright,  very  large,  stars  6th  to  llth  magnitude 

6940 

20     30 

27     58 

V 

very  bright,  very  large,  very  many  stars 

7078 

21     25 

11     44 

V 

very  bright,  very  large,  easily  resolved 

7089 

21     28 

-   1     16 

V 

bright,  very  large,  easily  resolved 

7092 

21     29 

48      0 

I 

very  large,  stars  7th  to  10th  magnitude 

7099 

21     35 

-23    38 

V 

bright,  large,  globular 

7243 

22     11 

49     23 

I 

large,  bright  stars 

7654 

23     20 

61       3 

I 

large,  many  stars 

7789 

23     52 

56     10 

I 

very  large,  very  many  stars 

TABLE  V.  —  NEBULAE. 


No. 
N.  G.  C. 

RIGHT 
ASCENSION. 

DECLINATION. 

MAP. 

DESCRIPTION. 

55 

Oh.  10m- 

-39°   46' 

II,  V 

very  bright,  very  large,  very  much  elongated 

221 

0      37 

40     19 

I,  II 

exceedingly  bright,  large,  round 

224 

0     37 

40     43 

I,  II 

exceedingly  bright,  large  and  elongated 

253 

0     43 

-25     51 

II,  V 

exceedingly  bright,  large  and  elongated 

598 

1     28 

30       9 

II 

very  bright,  very  large,  round 

613 

1     29 

-29     55. 

II 

very  bright,  very  large,  very  much  elongated 

650 

1     36 

51       4 

I 

very  bright  } 

651 

1     36 

51       5 

I 

very  bright  ) 

936 

2     23 

-   1     35 

II 

very  bright,  very  large 

1023 

2     34 

38    38 

II 

very  bright,  very  large  and  elongated 

1365 

3     30 

-36    32 

II 

very  bright,  very  large  and  elongated 

1535 

4     10 

-13       0 

II 

very  bright,  small,  planetary 

1559 

4     16 

-63       2 

VI 

very  bright,  very  large  and  elongated 

12 


EXPLANATORY  TEXT. 


No. 
N.  G.  C. 

EIGHT 
ASCENSION. 

DECLINATION. 

MAP. 

DESCRIPTION. 

1763 

4  h-  57  m. 

-66°   34' 

VI 

very  bright,  very  large 

1952 

5     28 

21     57 

11,  111 

very  bright,  very  large  and  elongated 

1976 

5    30 

-   5     27 

II,  III 

great  nebula  about  6  Orionis 

1977 

5     30 

-    4     54 

II,  III 

about  c  Orionis 

1978 

5     28 

-66     18 

VI 

very  bright,  very  large,  oval 

1982 

5     31 

-   5     20 

II,  III 

very  bright,  very  large 

1990 

5     31 

•   1     16 

II,  III 

very  large,  about  c  Orionis 

2024 

5     37 

-   1     54 

II,  III 

bright,  very  large 

2070 

5     39 

-69       9 

VI 

very  bright,  very  large,  looped 

2392 

7     23 

21       7 

III 

bright,  small,  round 

2403 

7     27 

65     49 

I 

quite  bright,  very  large  and  elongated 

2683 

8     46 

33     48 

III 

very  bright,  very  large  and  elongated 

2841 

9     15 

51     24 

I 

very  bright,  large  and  much  elongated 

2867 

9     19 

-57     53 

VI 

very  small,  planetary 

3031 

9     47 

69     32 

I 

exceedingly  bright  and  large 

3115 

10       0 

-   7     14 

III 

very  bright,  large  and  much  elongated 

3132 

10    ,  3 

-39     57 

III 

very  bright,  very  large,  oval 

3199 

10     13 

-57     28 

VI 

very  bright,  very  large 

3242 

10     20 

-18       8 

III 

very  bright,  blue  tint,  planetary 

3372 

10     41 

-59       9 

VI 

diffused  and  branching  about  rj  Carince  (Argus) 

3379 

10     43 

13       6 

III 

very  bright,  quite  large 

3587 

11       9 

55     34 

I 

very  bright,  very  large,  planetary 

3623 

11     14 

13     38 

III 

bright,  very  large 

3918 

11     45 

-56     37 

VI 

small,  round,  blue  tint,  planetary 

4254 

12     14 

14     59 

III,  IV 

bright,  large,  round,  three-branched  spiral 

4258 

12     14 

47     52 

I 

very  bright,  very  large  and  elongated 

4382 

12     20 

18     45 

III,  IV 

very  bright,  quite  large  and  round 

4565 

12     31 

26     32 

III,  IV 

bright,  very  large  and  elongated 

4594 

12     35 

-11       4 

III,  IV 

very  bright,  very  large  and  elongated 

4595 

12     35 

28     31 

III,  IV 

very  bright,  very  large  and  elongated 

4631 

12     37 

33     16 

III,  IV 

very  bright,  very  large  and  elongated 

4736 

12     46 

41     40 

I,  IV 

very  bright,  large 

4826 

12     52 

22     43 

IV 

very  bright,  very  large  and  elongated 

5128 

13     20 

-42     30 

IV,  VI 

very  bright,  very  large  and  elongated 

5194 

13     26 

47     42 

I 

great  spiral  nebula 

5236 

13     31 

-29    21 

IV 

very  bright,  very  large,  three-branched  spiral 

5367 

13     52 

—  39     30 

IV 

very  bright,  very  large  and  elongated 

6210 

16     40 

23    59 

IV 

very  bright,  very  small,  planetary 

6326 

17     13 

-51     38 

VI 

bright,  small,  planetary 

6369 

17     23 

-23    41 

IV,  V 

bright,  small,  annular 

6514 

17     56 

—  23      2 

IV,  V 

very  bright,  very  large,  trifid 

6523 

17     57 

-24    23 

IV,  V 

very  bright,  very  large,  in  cluster 

6543 

17     58 

66     38 

I 

very  bright,  small,  planetary 

6572 

18       7 

6     50 

IV,  V 

very  bright,  small,  planetary 

6618 

18     15 

-16     13 

IV,  V 

bright,  very  large,  two-hooked 

6720 

18     50 

32     54 

IV,  V 

bright,  quite  large,  annular 

6853 

19     55 

22     27 

V 

very  bright,  very  large,  double  condensation 

6905 

20     18 

19     47 

V 

bright,  small,  planetary 

6960 

20     42 

30     21 

V 

quite  bright,  large,  around  K  Cygni 

7009 

20     59 

-11     46 

V 

very  bright,  small,  elliptical 

7662 

23     21 

41     59 

I 

very  bright,  small,  blue  tint,  planetary 

NOTES   TO   TABLES   IV   AND  V. 

221.     Companion  nebula  to  the  Great  Nebula  in  Andromeda. 

224.  THE  GREAT  NEBULA  IN  ANDROMEDA.  It  is  plainly  visible  to  the  naked  eye,  and  is  the 
brightest  nebula  in  the  heavens.  It  has  a  nucleus  and  dark  streaks  which  in  the  photographs  are 
curved  as  if  indicating  a  spiral  structure. 


THE    COLORS   OF    STAliS.  13 

869,  884.  These  two  clusters  are  visible  to  the  naked  eye  and  are  designated  h  and  %  Persei, 
respectively.  They  are  magnificent  clusters  when  viewed  with  a  low-power  eyepiece. 

1952.     THE  CRAB  NEBULA.     It  is  so  named  from  its  appearance  in  Lord  Rosse's  reflector. 

1976.  THE  GKEAT  NEBULA  IN  ORION.  It  surrounds  0  Orionis,  which  is  visible  to  the 
naked  eye  as  a  single  star,  and  in  the  telescope  forms  the  group  of  four  principal  stars  and  two 
fainter  ones  known  as  the  trapezium.  The  rebula  is  the  largest  in  the  sky  and  has  a  great  rift  in 
it,  and  also  several  extensions  of  irregular  shape.  A  large  number  of  faint  stars  are  involved  in 
the  nebula. 

3372.  THE  NEBULA  AROUND  -q  CARLISLE  (ARGUS).  This  is  in  a  region  containing  many 
stars  forming  an  immense  cluster  involved  in  nebulous  matter.  The  star  77  Carince,  now  of  about 
seventh  magnitude,  was  of  extraordinary  brilliancy  in  1843,  exceeded  only  by  Sirius  ;  it  fluctuated 
very  much  in  brightness  between  1800  and  1870. 

5139.  This  cluster,  visible  to  the  naked  eye  and  known  as  u>  Centauri,  is  probably  the  most 
magnificent  in  the  sky.  It  contains  several  thousand  stars. 

5194.  THE  GREAT  SPIRAL  NEBULA.  It  was  so  named  by  Lord  Rosse.  It  is  not  very  con- 
spicuous in  small  telescopes,  and  its  structure  is  distinguishable  only  in  the  largest  instruments. 

6205.  This  cluster,  often  called  the  GREAT  CLUSTER  IN  HERCULES,  is  perhaps  the  most 
magnificent  visible  to  northern  observers.  It  is  very  densely  packed  with  faint  stars. 

6514.  THE  TIUFID  NEBULA.  It  contains  several  dark  rifts,  and  there  is  evidence  that  the 
nebula  lias  moved,  from  the  change  in  position  of  a  star  with  regard  to  one  of  these  rifts. 

6618.     THE  HORSESHOE  NEBULA.     It  shows  this  shape  only  in  large  instruments. 

6720.  THE  RING  NEBULA  IN  LYRA.  This  is  the  brightest  of  the  circular  nebulae  whose 
condensation  is  around  the  circumference  of  the  nebula  instead  of  at  its  centre. 

6853.     THE  DUMBBELL  NEBULA.     It  was  so  called  by  Lord  Rosse  from  its  double  condensation. 

7009.  Sometimes  called  the  Saturn  Nebula,  from  a  ring  seen  within  the  nebula  in  large 
telescopes. 

In  addition  to  the  clusters  of  Table  IV,  the  whole  Milky  Way  abounds  in  regions  in  which 
the  stars  are  closely  compressed,  and  a  telescope  with  a  low-power  eyepiece  will  reveal  many  bril- 
liant star  groups.  The  naked-eye  cluster,  the  Pleiades,  also  abounds  in  fainter  stars,  more  than  a 
thousand  having  been  counted  and  the  photographs  showing  a  nebulous  background  in  addition. 


THE    COLORS    OF    STARS. 

The  stars  vary  in  color  from  red  to  blue,  according  to  their  physical  condition.  The 
red  stars  are  in  many  cases  variable.  The  estimates  of  color  by  different  observers  are 
often  very  conflicting,  as  they  depend  not  only  upon  the  true  color  of  the  star,  but  also 
upon  the  condition  of  the  atmosphere,  the  color  imperfection  of  the  telescope  used,  and  the 
sensitiveness  of  the  observer's  eye  to  differences  of  tint.  Moreover  as  the  star  appears  as  a 
mere  point  of  light,  the  color  does  not  seem  as  pronounced  as  the  word  used  to  express  it 
suggests. 

In  this  atlas,  stars  of  a  red  color  are  indicated  by  the  letter  R  placed  as  a  subscript  to 
the  letter  or  number  designating  the  star.  If  the  star  has  no  letter  or  number  the  R  is 
placed  in  parenthesis.  Other  colors  than  red  are  not  indicated.  The  following  table  con- 
tains the  stars  which  are  charted  as  red,  in  which  the  color  is  especially  marked,  and  also  a 
few  of  other  colors  which  are  noteworthy. 


14 


EXPLANATORY   TEXT. 


TABLE  VI.  —  PROMINENT  COLORED  STARS. 


NAME. 

RIGHT 
ASCENSION. 

DECLINATION. 

MAGNI- 
TUDE. 

MAP. 

COLOR. 

8      Andromedse 

0  h-  34  m. 

30°   19' 

3 

II,  V 

Orange 

R     Sculptoris 

1     22 

-33       4 

var. 

II 

Red 

a      Eridani 

1     34 

-57     44 

1 

VI 

Red 

y      Andromedae 

1     58 

41     51 

2 

I,  II 

Orange 

o      Ceti 

2     14 

—   3     26 

var. 

II 

Red  at  maximum 

R     Trianguli 

2     31 

33     50 

var. 

II 

Red 

a      Ceti 

2     57 

3     42 

3 

II 

Orange 

-      Eridani 

4     30 

-   9     10 

6 

II 

Red 

a      Tauri 

4     30 

16     19 

1 

II 

Red 

R     Doradus 

4     36 

-62     16 

var. 

VI 

Red 

5      Orionis 

4     48 

2     21 

6 

II 

Orange 

R     Leporis 

4     55 

-14     57 

var. 

II 

Very  red 

£      Aurigae 

4     56 

40     56 

4 

1,11 

Orange 

a      Orionis 

5     47 

7     23 

var. 

II,  III 

Red 

5      Lyncis 

6     18 

58     29 

6 

I 

Very  red 

Aurigae 

6     30 

38     31 

6 

II,  III 

Very  red 

/n      Canis  Majoris 

6     51 

-13     54 

5 

III 

Very  red 

L2     Puppis 

7     10 

—  44     29 

var. 

III,  VI 

Very  red 

Puppis 

7     29 

-14     18 

5 

III 

Very  red 

Mali 

9       4 

—  25     27 

5 

III 

Red 

R     Leonis 

9     42 

11     54 

var. 

III 

Red 

U     Hydras 

10     33 

-12     52 

var. 

III 

Red 

/JL      Argus 

10     42 

-48     54 

3 

VI 

Red 

Centauri 

12     37 

—  48     16 

5 

VI 

Very  red 

R     Hydrae 

13     22 

-22     32 

var. 

IV 

Red 

R     Centauri 

14       9 

—  59     27 

var. 

VI 

Red 

a      Bootis 

14     11 

19     42 

0 

IV 

Yellow 

Trianguli  Australis 

15       5 

-69     42 

5 

VI 

Red 

/3      Librae 

15     12 

—   9       1 

3 

IV 

Pale  green 

<f>1     Lupi 

15     16 

—  35     54 

3 

IV 

Very  red 

X     Herculis 

16       0 

47     31 

var. 

I 

Red 

Scorpii 

16       2 

-26       3 

5 

IV 

Red 

a     Scorpii 

16     23 

-26     13 

1 

IV 

Very  red 

a1     Herculis 

17     10 

14     31 

3 

IV 

Orange 

•y      Draconis 

17     54 

51     30 

2 

I 

Orange 

4      Vulpeculaa 

19     21 

19    37 

5 

V 

Orange 

R     Cygni 

19     34 

49     58 

var. 

I 

Red 

X     Cygni 

19     47 

32     40 

'  var. 

V 

Red 

T     Cephei 

21       8 

68       5 

var. 

I 

Red 

/n      Cephei 

21     40 

58     19 

var. 

I 

Red 

8      Andromedae 

23     13 

48     28 

5 

I 

Red 

19     Piscium 

23     41 

2     56 

5 

II,  V 

Red 

R     Cassiopeiae 

23     53 

50     50 

var. 

I 

Red 

30     Piscium 

23     57 

-   6     34 

5 

II,  V 

Red 

VARIABLE  STARS.  15 


VARIABLE    STARS. 

In  this  atlas  are  included  variable  stars  whose  brightness  at  their  maximum  equals  the 
sixth  magnitude,  and  also  temporary  stars  which  at  their  brightest  were  visible  to  the  naked 
eye  but  now  require  a  telescope  or  are  wholly  invisible.  They  are  indicated  by  the  letter  F 
placed  as  a  subscript  to  the  letter  or  number  designating  the  star ;  if  the  star  has  no  letter 
or  number  the  letter  V  is  placed  in  parenthesis.  Variable  stars,  if  not  already  lettered,  are 
designated  by  the  later  letters  of  the  alphabet,  beginning  with  R,  followed  by  the  Latin 
genitive  of  the  constellation.  They  are  lettered  in  the  order  of  their  discovery,  and  after  Z 
is  reached  the  letters  'are  repeated  in  pairs,  RR,  RS,  etc. 

The  star  symbol  used  on  the  maps  corresponds  with  the  maximum  brightness,  except 
in  the  case  of  temporary  stars  now  invisible  to  the  naked  eye.  The  following  table  con- 
tains those  charted,  with  notes  regarding  the  changes  in  brightness  which  they  experience. 
The  list  is  made  from  Chandler's  Second  Catalogue  of  Variable  Stars.1  The  numbers  in 
the  first  column  are  those  of  that  catalogue.  Stars  of  the  Algol-type  are  those  which  are 
usually  at  their  maximum  brightness,  but  which  periodically  decrease  to  a  minimum  and 
return  again  to  the  maximum. 

The  variability  of  the  light  of  stars  is  of  especial  interest,  because  it  must  be  accounted 
for  in  any  theory  of  the  physical  state  of  the  stars.  Slow  changes  in  the  amount  of  light 
given  out  are  to  be  expected,  but  periodical  changes  require  special  explanation.  The 
greatest  interest  attaches  to  stars  of  the  Algol-iype,  which  are  most  naturally  accounted 
for  by  the  periodic  passing  between  us  and  the  star  of  an  eclipsing  body.  That  such  a  body 
exists  in  the  case  of  Algol  has  been  proved  by  the  periodic  displacement  of  the  lines  in 
the  spectrum  of  the  star,  so  that  the  star  and  its  companion  really  form  a  binary,  the  two 
revolving  around  their  common  centre  of  gravity.  Another  class  of  variables  exhibits  the 
light  change  in  a  manner  precisely  the  reverse  of  that  of  the  Algol  stars,  the  star  remaining 
at  its  minimum  brightness  the  greater  part  of  the  time  and  periodically  increasing  to  a 
maximum.  The  periods  are  not  always  the  same,  nor  is  the  brightness  at  the  successive 
maxima  uniform,  so  that  the  explanation  of  this  type  of  variability  is  not  simple  and  is  at 
present  quite  conjectural.  Another  class  of  variables  shows  continuous  changes  in  the  light, 
now  increasing  and  now  decreasing,  the  star  not  remaining  at  all  at  any  definite  degree  of 
brightness.  The  successive  maxima  and  minima  and  the  rates  of  change  are  often  variable 
also,  so  that  the  phenomenon  is  very  complicated.  Other  stars  occasionally  fluctuate  in 
brightness,  but  not  in  any  distinct  period  which  can  be  determined.  Another  class  of 
variables  includes  the  New  or  Temporary  Stars,  improperly  so  called  because  they  are  not 
new  creations,  and  it  is  only  the  great  increase  of  light  which  is  temporary.  In  every  case 
the  light  increases  rapidly  to  a  maximum,  and  decreases  more  slowly,  with  fluctuations 
that  are  remarkably  irregular  and  accompanied  by  changes  in  the  star's  spectrum  whose 
explanation  is  wholly  conjectural. 

»  The  Astronomical  Journal,  Nos.  300,  347,  369. 


16 


EXPLANATORY   TEXT. 


CO 

CO 

B 

tH 

d 

3 

3 

| 

O 

% 

0 

a 

S  o 

00 

iO 

o  ^ 

iH 

>, 

rfl        r*5 

.s 

PH 

3  a 

O>        &1 

bo   fc, 

>^i      ^ 

rr+ 

O 

cu    S 

PH    o 

5 

o 

o>    2 

S    f 

§S 
_0 

I 

a 
o 

rt     -^ 

r^H 

CO     '-§ 

Q 

•*j 

.5     "r 

£ 

O     c 

H 

pS 

43    o    <a 

d 

.2  S 

^cj 

^7n 

J    oil 

g 

*T3 

C^       CO 

'S  -^ 

5 

5 

| 

•H 

^j 

•^ 

S     r^ 

^ 

i-^ 

"rf       .          ^H 

O     60 

.5 

6p  ^^ 

.            ^_, 

t» 

-,    O     0 

O 

+a  ^3 

Si 

»H   .S 

rt           c3 

H 

M      QJ     rr^a 

88 

r^ 

1 

4 

S 

3 

9£                  _4J 

O 

rt      f5     ^ 

TH! 

,™         • 

I 

> 

W                 "^ 

fa 

,-r-J          O          ^ 

5 

H^     rv, 

1 

> 

^ 

CJ    1-^3 

^               O 

"     1-° 

o 

C*^ 

1 

5 

rH 

PH    fl 

I-T^ 

t—          *¥       ^ 

|         M       Q; 

a 

44 

O     f*i 

•§>  §> 

1 

1 

t 

3 

1 

S 
60 

•S  _g 

c3        n 

T3           S 

« 

CO 

o 

^"^                    —  H              ^J 

C 

-v                cQ 

bo 

> 

-M              ] 

CO 

"^j      f-l 

3 

•2 

fl              j 

) 

r& 

*             c3 

11° 

•2  "0  of 

H        fl      K_ 

£ 

li"' 

.PH      ^      C^l 

I  } 

1 

i 

o 

tl'       T—  t 

S         -t-9 

-4-3 

P 

2   S 
3 

D      F^i 

111    o  fe 
a,  o  " 

00 

* 

T^                 J 

! 

CO    "g 

S          o> 

S  £ 

Q}     TH 

!>>   co   ci.. 
13     co     0 

o 

^0    01 

t>,  01  oq 

"S    •  < 

o        2 

j 

?  s 

a      S 
co  ^ 

-4^"               4J~ 

^H                       ^H 

o          o 

e8     0)     ..     ., 
c3    d    C*    IS 

S                  03      JS 

g 

J    01    W 

"i    *    I 

j 

i 

s  'i 

TH      ° 

p 

i  S 

-i  i  *  ! 

|    g    |    £ 

O  OQ  [zj  M 

CO 

I 

r-J      r^     r^ 

bo  2    o 

CD    'C     ' 

E  8  8 

M  PH  PH 

11.1 

»    g    < 
PH  M  P 

1 

j 

j 

w     ^ 

^  g» 

,5  S 

J^i     HH 

.2  -~ 

.2       .2 

PH               H 
QJ              C3 

n  i          OM 

f 

h 

ao  ^ 

S    M 

HH3 

Ig 

tH 

00    C<) 

C-l 

CJ 

5 

b-     CO 

t~            10 

^H'CO    S 

01    COOOS 

Ol 

-    •< 

O    CO 

o 

0 

5 

CO    CM 

TH    CO             •* 

10    "* 

TH     TH     CO     •H* 

o 

«o 

"* 

O}    CO 

C-l 

^ 

5. 

01 

TH 

CO 

CO    CO             TH 

CO 

q  q 

• 

®    00 

S"5 

0 

CM    Ol 

o 

^ 

9 

s  " 

7    0>'            CO 

C-.    *    Oi 

t_ 

CM    iO    CN) 

t-  iO   i^ 

3 

1Q      ^      •*      °^      ^ 

iO    CO    b-    °? 

CM    iH    rt* 

V  V  ^  T  ^ 

5  ^ 

£  § 

1      T-H     «-     i^J 

rH    V 

o    1     | 

s  * 

TH 

T^    CO    ^^ 

CO    "^    0 

0    t~ 

V  ^  ^  ^.  "° 

^    CO    CO    ^ 

10  v* 

CO    «*             0    r 

H   TH 

S  S 

PH 

co 

CO    t- 

CO 

OS    OS             OS    Cl 

S 

S  S 

CO    CO 

o 

Tf 

CO 

CO 

b-    t- 

Ol 

a  - 

IO    00    TH    u, 

*-.i 

00 

•^   co  ^* 

t- 

b-  O 

•  ^ 

iO    TH    01    ^    05 

b-  iO  os  l>: 

Tin   °°'   -* 

"*    ^    b-    0    U 

5    00 

K  s 

1     1   A  <*i 

*~  id    1 

LO 

CO    CM    CO 

id  cd 

•^             CO       1      ^ 

cd  co  id    1 

Tji      1      CO 

1        1      CO    CD    T 

*      1 

•*  2 

TH    CO 

t-- 

c. 

) 

00 

o> 

o 

CO    CM 

O 

Spq 

id  >d 

T-i 

id 

id 

CO 

Tj3  id 

CO 

HH 

1 

h-T  H-T 

HH 
1—  1 
^  I—  1    1—  1 

M 

hH 
HH 

^        ~  ^ 

H    HH 

> 
HH    H-T  HH    HH 

c  1=1  s 

HH    H    HH    HH    t 
K^     HH     ,  K.^     H1 

4 
1 

H*    HH     f> 

p-     HH     f>     f>     H. 

H     HH 

B 

O 

P-     T-H     CO     OS 
CO              CO     iO 

CO    -^    CO 

Tj<                Oq 

s 

t>*  ^^  o^ 

Ol    CO    TH 

CO   O   t- 

TH    ^    U 

j 

^Sc^00^ 

-^SS  ct 

1C           CO 

S    iO                  if 

5    TH 

O 

O    OO    CO    iO 
O}    CO    CO    15 

O    CO    CO 

Tjl      CO 

CO 
CO 

CO    O    CM 

CO    -*    iH 

Ol      CO      T 

co.lr 

H    TH 

4 

CO           CM 

0    ^    CO    OS 

CO    01    CO 

S    TH     CO     CD     T 

i    Oi 

H     CO 

fi 

1 

1  1 

1  1  1 

1  '    1 

I'M" 

J 

~   £ 

a 

t~    OS    OS    IO 

TH      TH      TH      CO 

b—    (N    T^ 
CO    OI    TH 

TH 

CO 

OS   CM   id 
iO           IO 

CO    iO    if 

co  in  if 

S    O 

CO    O    OV    O    IO 
CM    iO            CM    CO 

00    O    iO    CD 

iO    TH    00 

O    Ol    CM    CO    P 

:  oo 

5    CO 

2  u 

i4 

o  o  o  o 

O    TH    01 

« 

OI    CO    CO 

•*•*•<; 

P« 

10    10    CO    CO    CO 

CO    b-    b-    b- 

b-    00    03 

TH      T- 

H    rH 

ca 

H 

1 

Ceti 
Andromedae 
Cassiopeiae 
Cassiopeiae 

Andromedae 
Sculptoris 
Ceti 

Trianguli 

1  1  1 

d>     O>     o3 

PH  PH  EH 

Doradus 
Aurigae 

3  .2 

LI 
j  h 

5  O 

d  -2  .2 
H   -J3  43 

S     0     0 

R    M    C 

E8  .2    2    o    § 
bo  B  .a    o    o 

's  .2  a  g  g 
4i  o  o  S  g 

Geminorum 
Puppis 
Canis  Majori 
Monocerotis 

111 
p-;3£ 

S  .2    S    8    8 
.3   a   13  .S  ^ 

3J|5» 

_O 
'c? 
3    ^ 

i  ffi 

J>  2 

J  & 

EH  HH*  PH"    cj 

GO  PH    o 

^ 

*•  CQ.  -< 

P^    w  P- 

!* 

H    s    P-  H  oc 

-HHPH& 

t>^^ 

.-      A^      ^^      r/%      '  — 

»« 

6 

§CM     CO     Oi 
rH    TH    O 

CM    O5    O 

0 

CM    O    iH 

t^    C71    TH 

•*      CO      T- 

iO    CO    t- 

H    O 

•    0 

iO     O»     TH     (—     b- 

O     CO     TH     b- 

iO    -r)l    O 

TH    Oi    O    CO    C 

i    01 

TH      TH      TH      O3 

CM    T)<    CO 

TH     TH     TH 

TH      TH      T- 

•    00 
1    iH 

2§o3o5c^ 

ololc^o^ 

SS3 

c^c^^c^^ 

VARIABLE  STARS. 


17 


• 

TH 

§ 

1                                                           1 

CO 

10 

§ 

t>^                             a 

1 

3 

Pn 
§                                                         60    fi 

eg                                        d    c« 

"43    c3 

a                                c   2 

1 

|        '•         1                               H             1 

(~i                                          "^                                                               ^*    ^                      'S 

cL 

1                                     1^         a 

& 

rH,                                                     -H                                                                               «        fi 

13                                     60                                                   3     8                     e« 

i 

TH                                                       „    aj                     CD 

1         ^            IS 

a                      53   °                          ^  .2'            .2 

, 

r-H      rrf                                                                 Tj      E                                 43 

1        g 

JS                   CO 

SCO             SJ     o    •*                                     B    ^                                           O 
TH             6O  -*H    O                                                                                           b— 

CO                       COCUgCC                                             ^    a                          -g                        CO 

IO                             TH 

^H                    TH             ^      ^  TH                                   J^    ^_j                     ^                    ,_( 

1-                     o 

O                     Oa>~.O                             O-g^                                               o 

r- 

1 

3 

^ 

OI     rf 

TJ    "9             "w 

30 

to 

0     60            fe 

60            L       6O    ^      bJO    L                             "^    .5     ^                     ^ 

J 

*         03                & 

,1 

CD      S                £ 

j 

« 

H 

B 

n 

PH      rH                  r^ 

^A^^PM^^        si^is:      ^      * 

t- 

0 

§ 

t-. 

05 

o 

TH 

CO 

01 

CM 

b- 

% 

CO                                                b-GCCOrHCJiCOrHCOCX 
O                                                                      b-                  TH    10           01           C 
CO                                                                                                   CO           TH           T 

5    b-    CO 
) 
1 

o 

CO 

00 

01 

oi 

®  co                           q          !3 

*| 

T^ 

t- 

iq 

^H 

TH 

C-l 

OI    O    M    «5 

OlSni'T'iOOst—   TH                 COCOb-^iOiOb-^b-^I          « 

^  b-  TH 

' 

;  °" 

1 
°1 

OS 

b- 

CO_ 

w 

w 

CO    CO    TH    OS 

b*\/    1     lcNicdco'id^~'^idcoid    1    TH'IOTH    1    id\/c"'c' 

5    TH    CO 

H 

T-H 

X 

rH 

TH 

IO    T-5                                                                           CO                            O 

TH                                                                                                                                                                TH 

»o 

>0 

oo 

eo 

CO 

CO 

IO    IO                                                                      b-                         TH           O           K 

5 

T- 

-1  co 

oo 

1- 

t- 

to 

b- 

04 

IO 

O    CO    ^   O 

ooidb^U5THOC£>THTj(OOOOC,id^oot-cococo« 

5    IO    CO 

/ 

^ 

1 

1 

t 

I 

1 

>o 

id 

id  id    1    oi 

cOb-^|       |iOCOcOTH/\          THiOidlcOTHTH'lidl 

co  id 

o 

IO 

*(«• 

c; 

CJ 

CO 

t-;  05                                                b-                  os        os        <: 

> 

*6 

eo 

id 

«S 

10 

id 

TH    10                                                                      TH                          id           10 

H 

M                                                           »..*..««b- 

- 

h 

'  f> 

> 

> 

r—  i 

> 

> 

M 

>  !>  >  > 

^M~   ££££££££££££>     r-T^HH^ 

•   t>   fc> 

H 

r^ 

K^     1"^ 

c 

5    CO 

•o 

rH 

t- 

O 

1- 

10 

b-    CO    CO    OI 

iH^COt-^Oa.iM^            lO^OOCi 

31OO1 

T 

H     IO 

"* 

** 

rH 

>o 

OI    OI    TH 

CO    ^^                      ^1^    CO    T^    ^H    C^    ^^    CO    ^O             ^j^    TH    C"$    ^^             IO    ^O             T 

<    TH    OI 

C 

•5     CO 

o 

C-l 

«O 

0 

b- 

<o 

w 

CO    CO    IO    CO 

t-C^C^»0(N^THCOTHt>.O500OlCCOt-COOOOO^t-C 

1    O    CO 

ll 

o 

Cl 

10 

01 

C-l 

i- 

OI    TH    OI 

T^C^^r-(THTH            COCMtNC^rH                    COO1^            iHT^C^C' 

5                 TH 

5  7 

1 

1 

1 

1 

1 

1            1               1    1    1    1        1        1 

T 

H  a 

« 

00 

OS 

CO 

0» 

ce 

CO   TH    CO   10 

OrHlOb-THOTHTHlOTHOSCOOIOICOb-OIOIOlTHCOt- 

•      t—      TH 

H| 

H      TH 

S3 

eS 

«5 

CO 

eo 

-t 

iO   TH   TH   iO 

THOlTH10THTHrHOlTHlOrHOlTHTHTH»O                    COTHT 

c 

5    01 

r. 

00 

CO 

«H 

TH 

-t 

-t 

TH   10   10   10 

COCOCOCOCOb-b-b-b-b-b-OOOOOOOOCOCC050>CT;OJO 

-     O^    O5 

•" 

H    T^ 

H    iH    rH 

to 

0 

._  .-i  .-.                                              8 

C 

2 

• 

.T-i 

r-l 

Q}     "^      Q) 

.2        .2  .2  3  .2  IS  .2  ^  "C  '  3  'fi  -^              m 

m     fR 

"i 

B    2 

3| 

53 

i 

s 

g 

•?c 

E 

1 

a 
® 

u 

TO 

'•§ 

o 

CO 

p 

w 

.2 

! 

S3         C         TO 

§   1   ^1 

__Q            ^            ^            f-| 

•--<      O      Q3      O 

g'p-g  S  .3  S  1  g.2i5SS  «  .H  03  9  coS'i"?  S'' 

i  §  1  1  1,  1  a  J  "i,*!*  y  y  1*1  1,1  !!'!'  *"§*  ' 

,  Jj  .2 

•o'Sn'Sb 

•>  5^  cs 

5  <i  CO 

B-  CO 

EH 

tf 

02 

M 

« 

^ 

M 

co  cd  oj  PH 

^H6o,o          etD^        «^[H^««I   ^W^rtS 

<r« 

1 

-    10 
H    CO 

— 

» 

i- 

o 

— 

b- 

CO 

a 

3 

TH      b-b-O, 

§S2T5S§5SgSSS?32?S§S^5^^g| 

>     TH     Oi 
J    C^    -^ 

c 
c 

o  TH 

ie 

X 

i 

o 

C-1 
10 

CJ 

CC 

CO    CO    CO    b- 

b-COOSOOTHTHOIOICO^lOCDb-b-b-b-cbcOOTHr 

H    rH    r-i 
-    b-    t~ 

18 


EXPLANATORY  TEXT. 


o 

n 
$ 


O 

Pi 

00     g 

Z  ft 

o    >^ 
f-  T3 

t«     C3 


s, 

0> 


a 

1 


GQ 


o 

CO 


CO      7-1 

CO    CO 
CO    i-l 


»o 


t-     O5 
CO    Ol 

CO    ^f 


M 

sg 

zZ 
~  a 

pq 


tO    <N» 

V  «> 


OS  t-; 

OS  CO' 

i  i  *s  »•  li  3 

I  I     CO    1C    ",   -<t 

1C  iH    iH  Y 

OS  to 


03 


« 
3 

H 


S. 


• 

s^ 

^2 


CO 


C-  =«>  W 

«  «?  T  f  co 

1C   »C     I       I 

Ol  O 

1C  »C 


1C   CO 


1C   O 


00    00 
1C    -^ 


COOO11C!OCOO>5O^O1OO 
•>*  »C  1CO1T-I  »CCO1C>C 


t-  •*  t-  00  -^ 

CO  CO  Ol  CO  ^ 


oo  o  t^  t-  in  o 

>n  co  in  CM  IH  in 


H  S 

§s 


•^COt-OOO10OOOl>CO3O3CO 
t-H    ^    T^  CO    CO   ^    7—1    Ol    *C   CO   1C 

ja 

OOOTHi-liHi-IOlOlOlCOCO 

O1O1O1O1O1O1O1O1O1O1O1O1 


.^H  <**    a>    i> 

a   e  £,  43 
O  O  K*  O 


'S  'a    *  -2    * 

S»  Sooi's  a 

u1  a"  6  S  o 


CD 

:3    a. 
t-    o 


oS 

o 


PH  H  H  H 


no 


in  O3  co  05  T^  b~™  co  ^^  co  co  01  c^ 

comoooicoooo5t^t-7-io 

Ol^'ftOb-t-ODCSOOlincO 
t-    t-t-t-t-t-t—b-OOCCCOCO 


DOUBLE  STARS.  19 


DOUBLE    STARS. 

The  double  stars  in  the  sky  number  many  thousands.  The  term  is  used  to  include 
those  stars  which  are  within  30"  of  each  other.  The  eye  cannot  separate  stars  unless  the 
distance  of  the  stars  is  very  much  greater  than  this,  so  that  a  telescope  is  necessary  for  the 
examination  of  these  objects. 

A  distinction  must  be  made  between  naked-eye  doubles  and  telescopic  doubles,  the 
latter  only  receiving  the  name  Double  Stars.  The  former  are  two  stars  whose  separation 
must  be  several  minutes  of  arc,  as  £  Ursce  Majoris  in  the  handle  of  the  Dipper,  and  e  Lyrce. 
The  former  is  evidently  two  stars,  but  the  latter  is  a  severe  test  for  the  unaided  eye,  just 
as  the  separation  of  each  of  its  components  into  two  stars  is  a  good  test  for  a  telescope. 
The  main  components  of  e  Lyrce  are  distant  3',  about  the  smallest  angle  which  the  eye 
can  distinguish. 

A  further  distinction  must  be  made  between  Double  Stars  and  Binaries.  The  former 
is  a  generic  term,  applying  to  all  stars  separated  by  less  than  30".  (Some  authorities 
would  adopt  even  a  smaller  limit,  as  15".)  The  latter  is  a  specific  term,  and  is  limited  to 
such  double  stars  as  are  proved  to  form  a  system,  the  two  stars  revolving  about  their 
common  centre  of  gravity.  The  aim  of  the  study  of  double  stars  is  the  detection  of  bin- 
aries, which  is  accomplished  by  observing  the  changes  in  the  relative  position  of  the 
component  stars.  The  existence  of  stellar  systems  is  a  definite  proof  of  the  universality 
of  attraction,  as  announced  by  Newton  when  he  formulated  the  law  of  gravitation. 

In  addition  to  the  binaries  ocularly  revealed  by  the  telescope  are  those  whose  com- 
ponents are  so  near  each  other  that  they  cannot  be  distinguished  with  the  telescope. 
They  have  been  detected  by  the  periodic  doubling  of  the  lines  of  their  spectra,  and  are 
known  as  spectroscopic  binaries. 

In  this  atlas  those  double  stars  only  are  included  the  brighter  component  of  which  is 
as  bright  as  the  sixth  magnitude,  and  the  other  as  bright  as  the  ninth  or  tenth  magnitude. 
The  list  therefore  contains  those  double  stars  which  are  seen  as  single  stars  with  the  naked 
eye,  but  which  may  be  seen  as  double  with  small-sized  telescopes.  These  stars  are  marked 
D  upon  the  maps,  this  letter  placed  as  a  subscript  to  the  letter  or  number  designating  the 
star.  If  the  star  is  without  letter  or  number  the  D  is  placed  in  parenthesis. 

The  following  table  contains  the  most  interesting  double  stars  of  those  charted,  com- 
piled from  various  authorities,  with  the  important  facts  regarding  each.  The  list  includes 
those  which  surely  form  a  binary  system,  and  also  those  which  are  optically  interesting 
because  of  contrast  of  color  between  their  components.  The  magnitudes  of  the  components 
are  given  and  the  position  angle  and  distance  of  each  pair.  The  position  angle  is  reckoned 
from  the  north  point  towards  the  east,  the  vertex  of  the  angle  at  the  brighter  component. 
The  position  angles  and  distances  of  the  stars  which  are  known  to  be  revolving  about  their 
common  centre  of  gravity  are  subject  to  change ;  the  values  given  are  necessarily  approxi- 
mate, but  are  sufficient  for  purposes  of  identification. 


20 


EXPLANATORY  TEXT. 


O     = 


-o 

1O 


oj     fl     cS 


s    " 


° 


§ 


a    a 


°  2  a  a  a 
f  *  8  5  § 


s 
9 
9 
oo 


-    ~     O 

rt  I  ^ 


"S  i  J 


u  pq  PH  PM  pq 


IO 


2  B 

eg 
s  * 
£« 


I  °  I  s  S 


1C    O 
CM    O 


O 
•*f 


<0 


O5    OO     t-     t- 

CO    T!<    CO    CO 


00 


CO    1O 


CO    t-    00 

rf  ^  *  i 

10"  IO     I 


CO 


IO    t-    00    IO    CO    CO    OO 

IO      TH      CO  *O      Tl<      Tj< 


O    t-    00    CO    O    OO    iH 
N    IO    iH    <M    <M    00    iH 


I  I 


f  O 
=  7 
O  !5 


^i 
OOOOi-liHrHi-lTHrHiM<M(NlNNCOCOCOTlH'^Tll>O»a>O>r5>O>OCOCOCOCOCO 


- 


§ 


a  &  a  a  a  's 

s    o 


.3  2  .3 

"      rrt        O 

q  .2 


^ 
53 


E 
O 


H 


III 


2      GO 
•r-4 


2      .2 

j*  -2    o> 


J?  S   1  B   e   3   i 

' 


a  ° 


?    ef 


.2    C 


§  i 
o  o 


K5 

10 


DOUBLE   STARS. 


21 


I 

tn 

•  PH 

M 

03 

O 

a) 

O 
to 

1      1 

bo 

||                                                                fo=                     T^H 

s 

TH 

rt 

TH 

ID                                   " 

3          .r-                                                rt 

^ 

^ 

ft              J3 

r^       Q3                                                 f3       H 

^ 

n 

"3       _g  'St                   _2  ^       "^ 

_g 

•  ' 

^3 

_J                                      CO 

°^               ••-«       £3                                                 CO     '*3                 03 

•^1                                      CO 

•^           C3     3                                 li     OQ            TO 

03 

42 

fl          be  P*                         ^    CQ         ^ 

- 

0 

«a 

ID 

a             S 

•^H       ^J      rt      ^                                            O     ^"^                <3J 
M     rT^       "       hD                                             '^       QJ                 CJ 

ID 

9 

-2                             03 

C3     p°      ^      ^                                            0      O                fl 

g 

i. 

S 

03           o>          -S 

fl       te     CO       S                                               "S       C3                "*^ 

—  - 

03 

**>        S         2  = 

o     O            ®                                  nn  "^     »•«    -S3 

H^> 

•4? 

M                r3                Q     TH 
fe*                 I                            CH 

«  P5    H"                                 cs  •£    d  Q 

S 

S 

03                te~                 .5 

2   ^'3  TJ                              "S 

bo      d       S       2  +3  a 

^                  r-H                                  „        H                   OQ 

S            ID          £H            o3     tn     o3           t-c 
o          ^j           ,p           o>    o>    o>           cs 

-       rt      >,      >,.3£      2 

&H          s^                    TH    Q)  b- 

0)             ff                             TH      0    O             TH 
>>     >              ,fl                M              TH      d     •<*              tO 

S     ^                                   0              ^     -S     Tj              Tj 

.2-2        g       'o       .2  .23  .2       | 

^        ^5        g           ^^'-SS 

§^a|      S        THgc^S 

.So3o            COoS            .2tO^(N 

bfl-S^      ^  -2        i^-S1-1 

gg-g^-T1            T3^3                p^Tj^eTj 

ao§bc        o..           joo/o 

.PH                            CH                '*"*     pq                 W     "~*               *2 

i 

a 

f 

riod  uncertain 

DQ 
I 

O 
!O 
Cl 

1 

I 

ID 

O 

i 

pP      q                                ^^               M    r™4      a 

p^                                            PH            PH            P 

.          '0;3<1'2        p^"^        Sft^p, 

PH 

T3 

*f 

9 

ft 

0) 

ID 
PH 

^>    ^       .    "M              „                   ^       ^      . 

-°      £             o5               r^s    l>j    £    l>>    £             > 

t^i 

-p 

-0 

b 

f>j 

r*' 

9 

>, 

i-Q     c3             p)  j            c3     c3     ^     c3     c3             ct 

£dO>  —  id<  —  idd*^          2ddddc 

3 

d 

'o 

1 

S 

s 

S 

^ 

C 

PH  pq       H       pq  pq  pq  pq  pq       pq 

WW^OWOpqpqH        <jpq«WPHpq 

P^ 

p^ 

fi 

?q 

M 

p; 

^ 

pq 

CO 

CC 

1O 

t—    SO    SO       ^  1O    ^f    CO                    COt—    TH 

O 
1  —  1 

IN 

«O 

rH 

CO 

Tj< 

>O 

°1 

1 

TH 

rH 

c<T 

0 

10 

a 

OOO-rHOOO              ,OOC 
OCOCO       ^CO(N»O                    THOC 
C^)INlNOiNiNlN              'iHTHCO 
O 

TH 

o        oooo        o3olftoo|O0 

SO 

TH 

I 

TH 

~ 
0 

CC 

0 

es 

CC 

0 
CO 

O 

-t 

IN 

t- 

TH 

o 

OS 

OC 

SO 

00 

CO 

SO 

0 

*° 

b- 

to 

1- 

to 

—  '      ;  j     —  ^               -^     f^j     )  •;     )  —  '     —     -  |     -J     ™ 

«    1O    SO    SO    TH    1O    iN    HH           CO    ^    !O    CN    1O    SO    ^ 

o 

TH 

'-•: 

— 

CO 

i^ 

>o 

SO 

»0~ 

10 

irT 

1—  1 

1—  1    >—  1    i—  i    ^           t—  l           1—  II—  II—  1 

1—  1 

t> 

^ 

> 

> 

<  —  i 

— 

I  —  i 

M 

M 

O    b-    CC    CO    SO    Ci    C^l    O    CO    TH    b"    tO 

10  S  S  S  §5  §  3  S  5  S  °  -  S  3  "  3 

o 

0 

T- 

o 

rH 

S 

CC 

« 

TH 

eo 

00 

CO 

<NlN^«b-b-SOt-C5-*O10<N 

THOt-TH<NGOOOOTHOO>«00"OSD-<J<<N 

oo 

o 

<o 

•»* 

1- 

OS 

00 

t» 

0 

(NCOCMTHiN            SO            1OC<1CV)C(; 

THCOTHTjHSOTH-*                  INCO                 T-I1OCO                  1O 

'- 

o 

T  —  1 

rH 

C1) 

TH 

•H* 

~+ 

CO 

III                          1 

1 

1 

1 

^^    00    CO    dO    ^H    C^    C^    CO    ^O    ^i^    ^^    CC 

W^OTHTHOtOb-OOTH-OUJOCOOOO 

to 

•-c 

t- 

O 

N 

rH<MCO             (N    ^t             C^-^iHIOrH 

THC^COTHiNCOCOCO^fiO                  (NCOCOi-i 

TH 

CO 

W 

CO 

•* 

•* 

TH 

TH 

b-    t~-    t—   CO    OO    CO    O^    C^    C^    O    O    T" 

THTHTHM<M^<N<N<NlNeOCOCOCOCO-* 

-t 

-t- 

-t 

-t 

-t 

-t 

10 

-0 

«5 

CO                 00                            Gf! 

s  s  a           _o      o         S 
S  S  S              i3      i3          £ 

M                            M       O                  M                 O 
O                Q)                         0)      S^                ^J                Ci 

M          '-3          .2                .2  '43         .2    oo  •£ 
*e        *•                         d    rt         a  "r*    « 

o         «         §               SI         ^og 

^              ,                   '^                C-t                         PH      ID                M     *r—  ^     ^ 

03          f>           a>   .,,            »£>           4>o3f> 

Borealis 

o    o    o              A  S        S             ^ 

p3     C     S    -^    -PH     83            co            w     CQ    ' 

.2     .2  s  2  «  §  '3  fg  a  '3  jg      a  '3  _« 

i 

'•~t 

2 

g 

9 

00 

S 

| 

artrt^OrrtKt-Wrtrtft 
H      M       p       Q       jT^     W      o      w      O      O      & 

O    O    O    O    O    M    t^    h^    \~~*    h-^    h^    t 

d     83     d     ^   'o     a    -*^   'Sn    a     2   'be    d     ^     3   'bi)  t? 
S    c    9    w    B    9    fl    1?  M    Q    C^  M    g    H    ?  5 

t-H1!—  '1-300^0  b^oo^o^ot^pq 

43 

a 

O 

^s 

O 

"o 

0 

K 

1 

0 

:q 

'^ 

0 

m 

o 

•$. 

1 

m 

"En 

o 
G 
o 
O 

sotj^xj,"     «  «     s-e-^-t*^ 

,     ^    b-    0    j,,      d^      ^-f-'0      8<I>'M*J.'«'*      « 

1 

a 

k 

^ 

w 

•UJ, 

-rH 

4. 

P. 

22 


EXPLANATORY  TEXT. 


§            c5 

-           1 

in 

W                       J*» 

3      1 

s       « 

3            S 

i 

04 

1 

I 

as               43* 

1       ^ 

-£             <s             $ 

fc"                             ^                                                               TH 

S             in              & 

2              '             t!             § 

a            £ 

c:     _           be 
£*q  .!!            O     M     to                  a 
-                   •*•*     c3            cu     fr-,     f"<                    w 
™                  „.    •*•»            t-<     c3     c3                  a)                  ^ 
a)                 l*'    P-<           o    G}    0}                 a^                 "" 

>>           £  g            >>  >>           & 

co              "   a            to  ^ 
t-    £,       pa    f          GO  as  co    >.,        g^^        . 

is        g        I  -1     «        » 

1  >,  S          '3          US           S 

i          >a               ft              "^    a>         ^               '  —  ' 

3  oc    ^               _,                g    °                            a) 

„   TH     00                       •£                         g      S                                             0 

:^°°                 0                 ^3^                §    &> 
3    o    o                             '3>  o         2,              "So 

S  S          <u  '§         U  'g  '§  3          o  3          I 

»^"i          as          1  "1     S          ^  S 

'O,    ft                      ft    ft    >>                      >> 

ft                        ~GO 

t>^                  t>^         •                    3        !^~                  t>-      ^^      fcfc!         3        Kfc^                     2        hfc^ 

f*>>>>^         S          ^to^         o3          ^>S*^a5>^ 

.S'S^1       §S        9aS2S'38S'J 
S        S  H        O1  M        S  PQ  S  PH  W  O  PH  S  C. 

5  .S  -2  .S        P        2  3  .2       -fi1       2  2  •&  2 
jpqpqpq       c?       WOW        H       pqpqHW 

w 
o 

i 

t-        "^ 

«                 0 

•< 

^41    «O      |         ^  2]    Q    CO    *O    CO    W    iH    CO    W5    *O            ^    C£ 

5    O^    C^-l    iH    ^*           ^~    ^    J«    CM    TH           CO    ^      1     ^^    ^ 

£ 

1-1         O 

eo                               |                    r-T 

S 

»     . 
O   H 

J§            0 

§                             °                   J2 

S3 

5§O§OlHS§o5§W0S°      "TH 

S  fc 

&* 

TH    „    ^    g    «    g    «    ^    C,    «    TH    TH    N    TH    ^    CO    C 

8              "  1*           1" 

CD 
H 

oo 

(C 

s 

^         t-T 

T-                                          ,H                            t~ 

b 

H 

g 

•^lO-*       ^COt_U5COTH-*CO5O-<tCOCO-*W 

?u>'<f<oiQ<£l<o<Gn<n<£^^inin     „<£ 

s 

+ 

us 

b 

>            >» 

•»>        > 

a 

£>>>!>>>•>          >•>•>.          &f  fe  fef  fef  fe 

B 

O 
H 

1O1OCO             COlH             •^iHTH-*COSx»CO»OTHO- 

jTHC^giSctg^^S^SS^^SS 

X 

o 

3 

o 

H 

iHcoiMTHTHTHeo»o«        CO>OO»THCMCOC> 

I^^^ScOTH^^^THTHCOTHCO00* 

a 

III            1               1 

1 

K 

a 

H    ° 

O    tD    Oi    C5    O    ?D    iH    CO    CO    CO    GO    CO    Ci    O    iH    O    b- 

•    GO    O    *O    CO    Y-H    ^    O    tr-»    C^l    *^*    CO    C^    <M    CO    ^*    C^ 

s  T 

CO    CO    CO    ^O                     ^H    £^    C^    C^    CO                     iH    TH    C^    V 

j  u5             c^i  ^  *o  TH  c^  Tj<  -^  co  ^  ^*  ^*  *o 

2    H 

rfl 

^    § 

.t-OOCOGOOOOOa>C5OiC50OOOOTH 

•< 

CO       CO                                     _CQ 

c^     ci                           c3 

CJ      O                                   D 
^<       tU                                   FH 

o    o                     o 

X 

en    CD    CG                          CO                                        .1-1 

•^GQ                ^COW^MCOCOO 

*rH      .f-»     .pH        m 

1   ,fl   ,C   ,13   .2                                                                       .^ 

J 

"22    "^    "^    *^^      2      Q    **^      r3C3rtC33S3r 

IllllllllillllllJ 

S22fl        8                  S6-2-S        S 
;  .2  .2  .2  g  «  rS  'S  'S  "5  5  -15  'S  ^  '3  "9  'S 

CO    *W     ?"•  ^JJ>    03,,     Sk      b       P*     £     ^    ^^     S.  "^       ^    ^^      Q.  J- 

1                            t~*         t™         '^                            TH                            ^*«                                   '         Vl"i.     1^             «*      **^                            ^^ 

a 


IH 

M 


DOUBLE  STARS. 


23 


1 


-3 

b 


tao 

o 
i— i 

b 
o> 

.1 

B 

o> 
P< 


'i  «s 


bbb 

•     OT     Oa 

a   B   a 

s  s  s    s  s  « 


c«     cS     03 

c    a    B 


o 

-f 


^  o        o 

.  'O  <N 

iH  iH 


IQ  O  >O  >O  lO  O  O 
CO  CO  00  T-t  -*  O5  Tf 
C^  CO  iH  CO  CO  rH  rH 


oot-cot-ioeot-t—  oot-oi 


co 


C5t— 


i-HiHTH-^H     (NCO     i-HrH^lO 


-  -  S8  „  :a 

•a  £  S  «  '?  S 


o 

00 


24  EXPLANATORY   TEXT. 


USE  OF  THE  STAR  ATLAS. 

The  following  suggestions  are  offered  for  the  assistance  of  those  using  the  atlas  for 
either  constellation  study  or  the  examination  of  the  sky  with  the  telescope. 

DESIGNATION    OF    STELLAR   POSITIONS   IN   THE   SKY. 

The  method  used  by  astronomers  for  designating  positions  of  the  heavenly  bodies 
should  be  understood.  This  is  precisely  the  same  as  that  of  designating  positions  on  the 
earth  by  their  longitude  and  latitude.  Upon  the  sky,  which  appears  to  us  as  a  sphere,  one 
half  of  whose  inner  surface  is  always  visible,  we  must  imagine  the  equator  to  be  drawn  and 
a  system  of  meridians  and  parallels  to  be  added.  The  celestial  equator  is  the  trace  upon 
the  sky  which  the  plane  of  the  earth's  equator  would  make.  As  we  see  it  from  any  point 
of  the  earth's  surface  except  the  poles,  it  passes  through  the  east  and  west  points  of  the 
horizon,  and  is  inclined  to  the  horizon  by  an  angle  which  is  90°  minus  the  latitude  of 
the  place.  Where  it  crosses  the  meridian,  it  is  distant  from  the  zenith  by  an  angle  equal 
to  the  latitude  of  the  place.  The  sun  in  its  daily  path  across  the  sky  describes  the  equator 
at  the  time  of  the  equinoxes,  about  March  20th  and  September  21st;  on  other  days  it 
describes  parallels  either  north  or  south  of  the  equator. 

The  pole  of  the  equator  is  the  fixed  point  in  the  sky  which  marks  the  prolongation  of 
the  earth's  axis.  It  is  always  due  north  of  the  observer  in  the  northern  hemisphere  or  due 
south  in  the  southern  hemisphere,  and  is  as  many  degrees  above  the  horizon  as  the  latitude 
of  the  place  of  observation.  Its  place  is  indicated  roughly  for  northern  observers  by  the 
second  magnitude  star  a  Ursce  Minoris,  or  Polaris,  and  for  southern  observers  by  the  fifth 
magnitude  star  a-  Octantis.  The  great  circles,  all  of  which  intersect  at  the  pole  and  are 
drawn  perpendicular  to  the  equator  at  its  several  points,  like  the  meridians  on  the  earth,  are 
called  in  the  sky  hour  circles,  not  meridians.  The  term  meridian  is  reserved  for  the  circle 
passing  through  the  pole  and  the  observer's  zenith.  Each  hour  circle  in  turn  momentarily 
coincides  with  the  observer's  meridian,  as  the  earth  turns  on  its  axis.  The  parallels  to  the 
celestial  equator  are  drawn  precisely  as  upon  the  earth.  They  are  called  parallels  of  decli- 
nation instead  of  parallels  of  latitude.  Each  of  the  heavenly  bodies  describes  the  equator 
or  one  of  these  parallels  as  the  daily  rotation  of  the  earth  on  its  axis  causes  it  to  move 
across  the  sky.  One  of  the  best  ways  of  fixing  the  whole  system  of  circles  in  the  mind  is 
to  watch  the  movements  of  the  heavenly  bodies  for  a  few  hours  on  some  clear  night,  having 
first  located  the  east  and  west  points  of  the  horizon  and  the  position  of  the  pole. 

Each  star  in  the  sky  has  an  hour  circle  passing  through  it,  just  as  each  point  on  the 
earth  is  upon  one  of  the  terrestrial  meridians.  The  distance  of  the  star  from  the  celestial 
equator  is  called  its  declination,  north  or  +  if  the  star  is  north  of  the  equator,  and  south  or  — 
if  south  of  the  equator.  This  corresponds  precisely  with  latitude  on  the  earth.  In  order 
to  get  the  other  measure  corresponding  with  longitude,  it  is  necessary  to  select  one  of  the 
hour  circles  as  a  reference  circle,  just  as  the  meridian  passing  through  Greenwich  is  chosen 
on  the  earth.  The  hour  circle  passing  through  the  point  on  the  celestial  equator  where  the 
sun  crosses  it  in  the  spring,  called  therefore  the  vernal  equinox,  is  selected  as  the  reference 
hour  circle.  It  is  called  the  equinoctial  colure.  The  hour  circle  at  right  angles  to  this, 
which  therefore  passes  through  the  sun's  solstitial  points  in  summer  and  winter,  is  called  the 
solstitial  colure.  The  angle  between  the  equinoctial  colure  and  the  hour  circle  passing 
through  any  star  is  called  its  right  ascension.  It  corresponds  with  longitude  on  the  earth, 


USE   OF   THE   STAR   ATLAS.  25 

with  the  exception  that  it  is  reckoned  from  the  equinoctial  colure  towards  the  east  all  the 
way  around  the  sphere,  amounting  therefore  to  24  hours  or  360°,  while  longitude  is 
reckoned  both  eastward  and  westward  from  the  meridian  of  Greenwich  and  therefore  does 
not  exceed  12  hours  or  180°.  Right  ascension  is  usually  given  in  hours,  minutes,  and 
seconds  instead  of  degrees,  minutes,  and  seconds,  just  as  is  frequently  done  in  expressing 
terrestrial  longitudes. 

It  is  a  great  help  to  a  living  appreciation  of  the  system  of  circles  above  described  and 
their  use  in  determining  the  right  ascension  and  declination  of  the  heavenly  bodies,  if  one 
will  take  the  trouble  to  estimate  the  right  ascension  and  declination  of  any  star,  and  then 
compare  them  with  the  true  values  given  on  the  chart.  To  do  this  it  is  necessary  first  to 
know  where  the  vernal  equinox  is  in  the  sky,  or  else  the  right  ascension  of  some  star  which 
can  be  used  instead  for  reference.  In  the  latter  case  the  difference  between  the  right  as- 
cension of  the  given  star  and  the  reference  star  is  estimated,  and  this  difference  added  to 
the  known  right  ascension.  It  is  wise  to  select  for  these  estimates  stars  in  different  parts 
of  the  sky. 

CONSTELLATION   STUDY. 

An  acquaintance  with  the  leading  star  groups  is  to  be  recommended  not  only  for  itself, 
but  because  it  gives  a  clearer  idea  of  the  motion  of  the  earth  on  its  axis  and  about  the  sun, 
and  also  of  lunar  and  planetary  movements.  It  is  well,  however,  to  remember  that  the 
tracing  of  the  old  figures  is  no  part  of  modern  Astronomy,  and  that  little  resemblance  is  to 
be  sought  between  the  names  of  the  constellations  and  the  stars  grouped  within  them.  It 
is  very  doubtful  if  the  ancient  astronomers  who  invented  this  method  of  designating  star 
groups  fancied  close  resemblances  between  the  groups  and  the  names  assigned.  In  only  a 
few  cases,  notably  those  of  a  snake-like  figure,  as  Draco,  Serpens,  and  Hydra,  is  it  possible  to 
detect  any  resemblance  whatever.  It  is  also  well  to  recall  that  the  constellations  occupy  a 
very  humble  position  in  the  modern  science  of  Astronomy,  as  their  use  is  simply  the  giving 
of  names  to  areas  in  the  sky. 

The  chief  difficulties  to  be  encountered  in  studying  the  constellations  arise  from  their 
changing  positions  in  the  sky  due  to  the  earth's  daily  motion  on  its  axis  and  its  annual 
motion  around  the  sun.  As  a  result  of  the  former,  the  same  constellation  appears  tipped 
at  a  different  angle  in  one  part  of  the  sky  than  in  another  a  few  hours  later.  As  a  result 
of  the  latter  the  constellations  appear  farther  westward  on  any  evening  than  they  did  at 
the  same  time  the  previous  evening.  The  remedy  for  these  difficulties  is  to  learn  the  con- 
stellations with  regard  to  each  other  and  not  with  regard  to  the  time  of  day  or  of  year,  and 
certainly  not  with  regard  to  terrestrial  objects. 

The  following  plan  is  suggested  for  a  systematic  study  of  the  constellations : 

1.  Divide  the  heavens  into  four  grand  divisions,  bounded  by  the  equinoctial  and 
solstitial  colures.  Trace  these  colures  in  the  sky  by  the  prominent  stars  near  which  they 
pass.  In  the  northern  sky  the  seven  stars  of  Ursa  Major  known  popularly  as  the  Dipper 
will  furnish  a  beginning.  The  two  stars  a  and  ft,  forming  the  side  of  the  bowl  of  the 
Dipper  and  known  as  the  "pointers,"  will  lead  to  the  pole  star,  a  Ursce Minoris,  by  pro- 
longing the  line  from  ft  to  a  to  about  five  times  its  length.  The  middle  star  of  the  seven, 
8  Ursce  Majoris,  at  the  junction  of  the  handle  with  the  bowl  of  the  Dipper,  and  the  faintest 
star  of  the  seven,  is  very  near  the  equinoctial  colure.  Imagine  a  line  connecting  the  pole 
star  with  8  Ursce  Majoris.  It  is  a  portion  of  the  equinoctial  colure ;  if  prolonged  from  the 
pole  star  beyond  8  Ursce  Majoris  it  will  intersect  the  equator  at  the  autumnal  equinox. 
The  star  77  Virginia  is  not  far  from  this  point.  If  prolonged  in  the  other  direction  from  8 


2G  EXPLANATORY  TEXT. 

Ursce  Majoris  beyond  the  pole  star  it  will  intersect  the  equator  at  the  vernal  equinox. 
There  is  a  line  of  bright  stars  easily  traced  which  marks  the  way,  made  up  of  /8  Cassiopeice, 
a  Andromedce,  and  j  Pegasi.  The  first  of  these  is  in  the  foot  of  the  chair-shaped  figure 
which  is  the  characteristic  figure  of  Cassiopeia  ;  the  second  and  third  form  the  eastern  side  of 
the  conspicuous  quadrilateral  known  as  the  "  Square  of  Pegasus."  The  vernal  equinox  it- 
self is  in  the  relatively  starless  region  south  of  y  Pegasi  ;  the  line  from  a  Andromedce  to  y 
Pegasi  should  be  prolonged  as  far  beyond  the  latter  as  they  are  apart.  After  the  equinoc- 
tial colure  has  been  traced  as  above,  and  the  vernal  and  autumnal  equinoxes  located,  the 
solstitial  colure  may  be  similarly  traced  at  right  angles  to  the  above.  It  will  lead  nearly  to 
77  Geminorum  for  the  summer  solstice,  and  in  the  reverse  direction  to  p.  Sagittarii  for  the 
winter  solstice. 

2.  Learn  the  zodiacal  groups.     Each  of  these  has  a  characteristic  figure,  by  which  it 
may  be  recognized.     The  groups  are  of  first  importance,  because  in  them  lies  the  ecliptic 
or  the  suix's  path  through  the  heavens,  and  also  the  paths  of  the  moon  and  leading  planets. 
It  is  advisable  to  note  from  the  maps  just  where  the  ecliptic  itself  passes  among  the  stars 
of  these  groups. 

3.  Add  the  leading  constellations  north  and  south  of  the  zodiacal  groups,  and  later 
the  less  conspicuous  groups.     At  first  only  the  leading  stars  should  be  noted,  the  fainter 
ones  to  be  added  later  if  desired. 

4.  Learn  the  twenty  stars  usually  known  as  stars  of  the  first  magnitude. 

The  constellations  are  best  learned  by  their  characteristic  figures.  In  order  to  aid  in 
this  study,  six  smaller  maps  precede  the  main  maps  of  the  atlas.  Their  outlines  and 
general  plan  are  precisely  the  same  as  those  of  the  larger  maps.  They  contain  the  stars 
down  to  the  fourth  magnitude,  with  a  few  fainter  stars  where  necessary  to  complete  a 
characteristic  figure.  In  many  cases  there  is  no  question  as  to  what  constitutes  the  leading 
stellar  figure  of  any  constellation  area,  but  in  others  different  observers  may  sometimes 
differ  as  to  the  figures.  The  connecting  lines  which  are  drawn  upon  these  maps  are 
intended  as  guides  to  help  in  tracing  the  characteristic  figures.  It  is  to  be  expected  of 
course  that  different  students  will  oftentimes  prefer  different  arrangements  to  those  here 
presented. 

The  student  who  is  interested  in  the  historical  development  of  the  subject  may  profit- 
ably refer  to  the  larger  maps  and  note  the  outlines  of  the  old  figures  in  their  relation  to  the 
actual  stellar  figures. 

In  order  to  facilitate  the  study  of  the  constellations  in  an  orderly  way,  a  rearrange- 
ment of  the  constellations  according  to  the  four  divisions  of  the  sky  is  here  given.  The 
circumpolar  constellations  of  all  four  divisions  can  best  be  studied  together,  but  the  equa- 
torial constellations  of  the  four  divisions  by  themselves.  For  this  reason,  the  maps  of  this 
atlas  are  arranged  as  two  circumpolar  maps,  and  the  intermediate  parts  of  the  sky  in  four 
divisions  bounded  by  the  equinoctial  and  solstitial  colures.  The  Roman  numerals  I,  II, 
III,  and  IV  refer  to  the  four  divisions  respectively.  The  zodiacal  constellations  are 
printed  in  small  capitals,  and  the  other  original  constellations  of  Ptolemy's  list,  which 
have  the  most  conspicuous  figures  in  the  northern  sky,  in  italics.  Where  a  constellation 
area  is  partly  in  one  and  partly  in  another  division,  it  is  here  listed  in  the  division  in 
which  the  greater  part  of  its  area  lies. 


USE    OF   THE  STAR  ATLAS. 


27 


TABLE  IX.  —  CONSTELLATIONS  ARRANGED  ACCORDING  TO  THEIR  POSITION  IN  THE  SKY. 


NORTHERN  POLAR. 

I. 

II. 

III. 

IV. 

Cassiopeia 

Lynx 

Ursa,  Minor 

Cygnus 

Camelopardalis 

Ursa  Major 

Draco 

Lacerta 

Perseus 

Cepheus 

EQUATORIAL  I. 

EQUATORIAL  II. 

EQUATORIAL  III. 

EQUATORIAL  IV. 

Andromeda 

Leo  Minor 

Coma  Berenices 

Lyra 

Triangulum 

GEMINI 

Canes  Venatici 

Aquila 

Auriga 

CANCER 

Bootes 

Sagitta 

PISCES 

LEO 

Hercules 

Vulpecula 

ARIES 

Monoceros 

Corona  Borealis 

Delphinus 

TAURUS 

Canis  Minor 

Ophiuchus 

Equuleus 

Cetus 

Sextans 

Serpens 

Pegasus 

Eridanus 

Hydra 

VIRGO 

Scutum 

Orion 

Crater 

LIBRA 

SA(iITTARIUS 

Lepus 

Canis  Major 

SCORPIUS 

CAPRICORNUS 

Sculptor 

Argo  (Puppis) 

Corvus 

AQUARIUS 

Fornax 

(Malus) 

Lupus 

Microscopium 

Cselum 

Antlia 

Piscis  Australis 

Colurnba 

SOUTHERN  POLAR. 

I. 

II. 

III. 

IV. 

Phoenix 

Argo  (Vela) 

Centaurus 

Corona  Australis 

Horologium 

(Carina) 

Norma 

Grus 

Hydrus 

Volans 

Ara 

Telescopium 

Reticulum 

Chamaeleon 

Crux 

Indus 

Dorado 

Circinus 

Tucana 

Pictor 

Musca 

Pavo 

Mensa 

Triangulum  Australe 

Octans 

Apus 

The  names  of  the  months  given  at  the  margins  of  the  star  maps  show  the  times  of 
year  when  the  constellations  can  best  be  studied  in  the  evening.  The  names  are  placed  be- 
neath the  hour  circles  which  correspond  with  the  meridian  at  9  P.M.  local  time.  On  the 
circumpolar  maps  the  names  are  placed  under  the  hour  circles  which  extend  from  the  pole 
downward  to  the  horizon  at  the  time  named.  To  illustrate,  —  suppose  that  the  heavens 
are  to  be  examined  October  1st,  9  P.M.  Map  V  shows  that  at  that  time  the  hour  circle 
which  marks  the  right  ascension,  21  h.  40  min.,  nearly  coincides  with  the  meridian. 
The  constellations  west  of  the  meridian  are  those  west  of  this  hour  circle  and  are  given  on 
Map  V;  those  east  of  the  meridian  are  partly  on  Map  V  and  Map  II.  Map  I  shows  how 
the  northern  constellations  appear  to  a  person  in  the  northern  hemisphere  when  the  page 
is  turned  so  that  the  date  is  at  the  bottom.  Cassiopeia  is  below  the  pole  towards  the  left, 
Ursa  Major  high  in  the  sky  above  the  pole.  The  following  table  is  given  to  aid  still 
further  in  determining  the  position  of  the  constellations  at  different  times  of  the  year.  It 
gives  the  right  ascensions  which  coincide  with  the  meridian  at  9  P.M.  on  the  dates  named. 


28 


EXPLANATORY  TEXT. 


TABLE  X.  —  SIDEREAL  TIME  AT  9  P.M.,  OR  RIGHT  ASCENSION  OF  THE  HOUR  CIRCLE 

WHICH    COINCIDES   WITH   THE    MERIDIAN    OF    THE    OBSERVER. 


January      1      3  ^  45  m. 
15      4     40 
February     1      5     47 
15      6     42 
March          1      7     37 
15      8     32 

April           1        9h.39m. 
15      10     34 
May             1      11     37 
15      12     33 
June            1      13     40 
15      14     35 

July             1      15  h.  38m. 
15      16     33 
August        1      17     40 
15      18     35 
September  1      19     42 
15      20     38 

October       1      21  h.  41  m, 
15      22     36 
November   1      23     43 
15        0     38 
December    1        1     41 
15        2     36 

The  maps  giving  the  constellations  near  the  equator,  Maps  II-V,  are  arranged  with 
the  west  toward  the  right  and  the  east  toward  the  left,  just  as  the  sky  appears  to  a  person 
in  the  northern  hemisphere  when  facing  south.  If  the  atlas  is  used  in  the  southern  hemi- 
sphere, the  page  is  to  be  inverted.  The  equator  is  drawn  as  a  horizontal  line ;  it  must  be 
remembered  that  in  the  sky  it  is  a  semicircle  which  extends  from  the  eastern  point  of  the 
horizon  to  the  western  point,  and  that  where  it  crosses  the  meridian  it  is  distant  from  the 
zenith  by  an  amount  equal  to  the  observer's  latitude.  Therefore,  if  the  map  is  held  so  that 
the  hour  circle  which  is  on  the  meridian  is  nearly  vertical,  the  equator  at  both  the  left  and 
the  right  will  gradually  approach  the  horizon,  touching  it  at  hour  circles  six  hours  greater 
and  less  than  that  on  the  meridian.  If  one  views  the  constellations  facing  the  east  or 
west,  he  may  turn  the  atlas  so  that  the  equator  as  drawn  will  make  an  angle  with  the  ver- 
tical equal  to  the  latitude  of  the  place,  and  the  star  groups  will  appear  at  about  the  angle 
which  they  have  in  that  part  of  the  sky. 


TELESCOPIC   STUDY. 

The  atlas  is  designed  to  assist  those  with  small  telescopes  who  may  desire  to  find 
objects  in  the  sky.  For  this  reason,  in  addition  to  the  stars  readily  visible  without  a  tele- 
scope, the  leading  clusters,  nebulas,  double  stars,  red  stars,  and  variables  have  been  located 
on  the  maps.  The  number  of  stars  of  the  fainter  magnitudes  visible  in  a  telescope  of  only 
2  inches  aperture  is  so  large  that  they  could  not  be  charted  without  crowding  the  maps. 
The  stars  charted  can  be  seen  with  the  naked  eye  and  examined  themselves,  or  used  as 
starting-points  from  which  to  find  the  other  objects  charted.  The  lists  given  in  the 
preceding  pages  contain  the  leading  objects  of  each  class  in  the  sky. 

It  is  well  to  know  what  can  be  expected  of  any  given  telescope.  One  of  2  inches 
aperture  will  show  stars  as  faint  as  the  10th  magnitude  ;  of  4  inches  aperture,  as  faint  as 
the  12th  magnitude ;  of  10  inches  aperture,  as  faint  as  the  14th  magnitude.  But  stars  on 
the  extreme  limit  of  brightness  thus  stated  can  be  seen  only  when  atmospheric  conditions 
are  good  and  the  instrument  well  focussed  for  the  observer's  eye.  The  dividing  power  of  a 
telescope  in  the  examination  of  double  stars  depends  upon  the  magnifying  power  used  and 
also  upon  the  steadiness  of  the  atmosphere  and  the  magnitudes  of  the  components.  The 
magnifying  power  of  the  telescope  under  ordinary  atmospheric  conditions  is  rarely  more 
than  20  or  30  times  the  aperture  of  the  telescope  in  inches.  Familiarity  with  the  instru- 
ment and  its  different  eyepieces  will  show  the  observer  what  eyepieces  are  best  adapted  for 
use  under  different  conditions.  Double  stars,  the  distance  of  whose  components  is  less  than 
2"  or  3".  are  difficult  objects  for  the  amateur  to  divide  with  telescopes  under  6  inches 
aperture,  especially  if  the  components  are  bright.  The  quadruple  star  e  Lyrce  is  an  excel- 
lent object  with  which  to  test  the  capacity  of  the  telescope  for  this  kind  of  observing. 


USE   OF  THE  STAB  ATLAS.  29 

In  order  to  use  the  star  chart  to  find  objects  invisible  to  the  naked  eye,  when  the  tele- 
scope is  not  provided  with  setting  circles,  it  is  well  to  know  the  diameter  of  the  field  of 
view  in  minutes  of  arc.  This  will  differ  for  different  eyepieces,  diminishing  as  the  magni- 
fying power  increases.  It  can  be  determined  in  several  ways,  as  (1)  by  estimating  the 
diameter  of  the  field  in  terms  of  the  diameter  of  the  moon  seen  with  the  given  eyepiece. 
The  moon's  diameter  is  about  32'.  (2)  By  determining  the  time  which  it  takes  a  star  to 
move  centrally  across  the  field,  the  telescope  remaining  at  rest.  If  the  star  is  near  the 
equator  and  the  time  is  expressed  in  minutes  and  a  fraction,  simply  multiplying  by  15  will 
give  the  diameter  of  the  field  in  minutes  of  arc.  If  the  star  is  not  near  the  celestial  equa- 
tor,, the  resulting  value  will  be  too  large  and  must  be  multiplied  by  the  cosine  of  the  star's 
declination.  When  the  diameter  of  the  field  is  known,  it  is  easy  to  move  the  telescope 
from  a  star  towards  which  the  telescope  may  be  directed  a  sufficient  amount  to  bring  the 
desired  object  into  the  field.  If  the  object,  for  instance  a  nebula,  is  on  the  star  map,  its 
distance  and  direction  from  a  star  visible  to  the  naked  eye  may  be  estimated,  and  the 
former  converted  into  diameters  of  the  field  of  the  telescope.  If  an  object  not  upon  the 
map  is  to  be  examined,  for  instance  a  comet,  it  may  be  located  upon  the  map  by  its 
right  ascension  and  declination,  and  then  its  relation  to  some  star  determined. 

Nebulas  are  usually  disappointing  objects  in  a  small  telescope.  The  descriptions  pub- 
lished describe  them  as  they  appear  in  very  large  instruments.  Very  few  of  them  are  suf- 
ficiently bright  to  show  much  detail  of  structure  unless  the  telescope  is  of  at  least  12  inches 
aperture. 

The  colors  of  stars  are  usually  not  so  marked  in  the  telescope  as  one  might  expect. 
The  uncorrected  color  of  the  telescope  itself  and  the  color  added  by  the  atmosphere,  espec- 
ially if  the  star  is  near  the  horizon,  give  a  spurious  tint  which  must  not  be  confounded  with 
the  real  color  of  the  star.  It  is  also  very  necessary  for  noting  colors  of  the  star  that  the 
telescope  should  be  well  focussed.  The  stars  marked  red  are  usually  of  a  less  pronounced 
shade  of  red  than  the  word  might  seem  to  indicate. 

In  the  use  of  a  telescope  too  little  attention  is  often  given  to  the  firmness  of  the  sup- 
port of  the  telescope  and  to  a  careful  focussing  for  the  individual  eye  of  the  observer.  Care 
in  these  matters  will  enable  the  observer  to  use  the  instrument  to  better  advantage,  and 
experience  will  often  show  that  its  capabilities  are  much  greater  than  at  first  supposed. 


CHARACTERISTIC    CONSTELLATION    FIGURES. 


MAPI 

RIGHT  ASCENSION  O^xxiv 
DECLINATION  +  40°-+9Q 


CONSTELLATIONS 

AROUND 

NORTfl  POLE. 


•  BRIGHTER~THAN 

•  I^MAQ. 

•  2°  MAG 


•  3°  MAG. 

•  4™A\AG. 

•  5THMA& 


RIGHT  ASCENSION  O>1-VI1' 


MAP  II 


DECLI  NATION  -  40  °- +  40° 


RIGHT   ASCENSION  VIK  —  XIIK 


MAP  III 


DECUNATION-40"-  »40° 


• ' Tl      CRATER 


•  BRIGHTER  THAN  I5T  MAG.     •  I"  MA.G.        •  2°  MAG.      •  3°  MAS.      «4T"A\A&. 


RIGHT     ASCENSION,  XHh  —XVIII' 


MAP     IV 


DECUNATION.-40    -<~4O 


RI6HT    ASCENSION,    XVIII    -  XXIV 


MAP  V 


OE;CLINATION,-40°—  *-40° 


•  BRIGHTER  THAN  hT  MAG 


'4'"MAG.     •  5'"MA& 


MAP  VI 

RIGHT  ASCENSION  Oh-XXIVh 
DECLINATION-40--90 


CONSTELLATIONS 

ABOUND      5QUTH 


MAP  I. 

Right  Ascension,  Oh — XXIVh. 
Declination,*  40° — +S0° 


SYMBOLS. 

<J  brighter  than  1st  Mag. 
&  1st  Mag. 

#  2nd  Mag. 
.$•  3rd  Mag. 

#  4th  Mag. 
+  6th  Mag. 
'   Gth  Mag. 


CONSTELLATIONS 

AROUND 
NORTH  POLE 


SYMBOLS. 

0  fainter  than  6th  Mag. 

»     red. 

v    variable 

»    double 
—  two  stars 
•SS  cluster 
©  nebula 


Right  Ascension,  O  h  — VI  h 


brighter  than  1st  Mag.     &  1st  Mag.       %  end  Mag.       #  3rd  Mag.       *  4th  Mag. 


Mag.        •  6tfi  -M 


II. 


Declination,— 40° H  40° 


XXIII 


°  fainter  than  6th  Mag.        *  red.        v  variable.        »  double.  two  stars.      •iff  cluster.        si:  nebula. 


Right  Ascension,  Vlh. Xllh. 


III. 


EN  A 


brighter  than  1st  Mag.       %f  1st  Mag.       ^  ^d  Mag.       ^  3d  Mag.       *4thMag.        +  5th  Mag.         •  6th  Mi 


Declination  r-  40- \-40" 


fainter  than  Oth  Mag.        n  red         v  variable. 


.     —   hw  s^ars.       ©  c/usfer. 


Right  Ascension,  Xllh—XVIIIh. 


MA 


XIX 


XVIII 


20  XVII 


XVI 


brighter  than  1st  Mag.     %fc  1st  Mag.       #  ^nd  Jfagr.       ^  5rd  Jlfagr.       *  4th  Mag.       -f  5</i  Magr.        •  6th  M 


Declination — 40 \-lfi 


fainter  than  6th  Mag.        B  red.       *  variable.       D  double.  two  stars.      i&  cluster.        eft  nebula. 


Right  Ascension,  XVIIIh. A'.YfWi. 


IS 


10 


10 


15 


20 


25 


— "STo—  >... 


A\    16 
+*x*          * 


"m 


-'V^;    V*. 


%  \    A  /  Q 


nR          I     +    U 


V    W 

.  *  ^  vi^l 

\*>^p 

\  v>    i.  f 

\  Jik  ^J7 

'     :«4««/» 

i.     \  \x  I         + 

»         4,  *#- 

\        ^^  ,*-  •     / 

I       +*< 

'  <^ 

49        ,^''T  "~~       '-^  ' 

.  _,'^B)  8    ---V 

/  T"" ;  i       '  ^1 


--— * ~L  -»• 

,_- "--         4> V 


O     O      TO 


brighter  than  1st  Mag.     %  1st  Mag.       #  ^nd  Jlfagr.       *  5rd  Jtfagr.        *  4th  Mag.       -f  5*ft 


6th  J 


V. 


Declination^-  40°—  +40" 


4O SO 


xym 


XVII 


«  fainter  than  6th  Mag.        B  red.       v  variable.       D  double.  two  stars.      «S  cluster.        as  nebula. 


MAP  VI. 

Right  Ascension,  Oh — XXIVh. 
Declination— 40- 90° 


SYMBOLS. 

&  brighter  than  1st  Mag. 
0  1st  Mag. 

#  2nd  Mag. 

#  3rd  Mag. 

*  4M  Mag. 
+  5th  Mag. 

•  6th  Mag. 


•    <t 


-f 

(01 


CONSTELLATIONS 

AROUND 
SOUTH  POLE 


#•' 


* 


#• 


%* 


"  t, 


t 


.*• 


X    I 


* 


^J7V' 


C/) 


b 


fl 


* 


o 


s, 


-p. 


\  * 


* 

A. 


IV 


% 


o 


o 


*•'-.. 


<b* 


o 


L/0 


\* 


• 


.** 


flr 


K 
* 


jj. 


°^. 


SYMBOLS. 

«  fainter  than  6th  Mag. 

B    red. 

T    variable 

»    double 
—  two  stars 
$£  cluster 
©  nebula 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 
LOAN  DEPT. 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


Ht»WWWA 

-j,t./^,r>     ,     ~ 

firr\  o       4QC3 

SEP  * 

LIBRARY  USB 

MAR  3  0  1961 

D  i_O 

1        MM^so  1961 

General  Library 
LD  21A-50m-8,'57                                  University  of  California 
(C8481slO)476B                                                   Berkeley 

188 


1 


